drop table if exists t1,t2; set @my_binlog_cache_size =@@global.binlog_cache_size; set @my_connect_timeout =@@global.connect_timeout; set @my_delayed_insert_timeout =@@global.delayed_insert_timeout; set @my_delayed_queue_size =@@global.delayed_queue_size; set @my_flush =@@global.flush; set @my_flush_time =@@global.flush_time; set @my_key_buffer_size =@@global.key_buffer_size; set @my_max_binlog_cache_size =@@global.max_binlog_cache_size; set @my_max_binlog_size =@@global.max_binlog_size; set @my_max_connect_errors =@@global.max_connect_errors; set @my_max_connections =@@global.max_connections; set @my_max_delayed_threads =@@global.max_delayed_threads; set @my_max_heap_table_size =@@global.max_heap_table_size; set @my_max_insert_delayed_threads=@@global.max_insert_delayed_threads; set @my_max_join_size =@@global.max_join_size; set @my_myisam_data_pointer_size =@@global.myisam_data_pointer_size; set @my_net_buffer_length =@@global.net_buffer_length; set @my_net_write_timeout =@@global.net_write_timeout; set @my_net_read_timeout =@@global.net_read_timeout; set @my_query_cache_limit =@@global.query_cache_limit; set @my_query_cache_type =@@global.query_cache_type; set @my_rpl_recovery_rank =@@global.rpl_recovery_rank; set @my_server_id =@@global.server_id; set @my_slow_launch_time =@@global.slow_launch_time; set @my_storage_engine =@@global.storage_engine; set @my_thread_cache_size =@@global.thread_cache_size; set @`test`=1; select @test, @`test`, @TEST, @`TEST`, @"teSt"; @test @`test` @TEST @`TEST` @"teSt" 1 1 1 1 1 set @TEST=2; select @test, @`test`, @TEST, @`TEST`, @"teSt"; @test @`test` @TEST @`TEST` @"teSt" 2 2 2 2 2 set @"tEST"=3; select @test, @`test`, @TEST, @`TEST`, @"teSt"; @test @`test` @TEST @`TEST` @"teSt" 3 3 3 3 3 set @`TeST`=4; select @test, @`test`, @TEST, @`TEST`, @"teSt"; @test @`test` @TEST @`TEST` @"teSt" 4 4 4 4 4 select @`teST`:=5; @`teST`:=5 5 select @test, @`test`, @TEST, @`TEST`, @"teSt"; @test @`test` @TEST @`TEST` @"teSt" 5 5 5 5 5 set @select=2,@t5=1.23456; select @`select`,@not_used; @`select` @not_used 2 NULL set @test_int=10,@test_double=1e-10,@test_string="abcdeghi",@test_string2="abcdefghij",@select=NULL; select @test_int,@test_double,@test_string,@test_string2,@select; @test_int @test_double @test_string @test_string2 @select 10 1e-10 abcdeghi abcdefghij NULL set @test_int="hello",@test_double="hello",@test_string="hello",@test_string2="hello"; select @test_int,@test_double,@test_string,@test_string2; @test_int @test_double @test_string @test_string2 hello hello hello hello set @test_int="hellohello",@test_double="hellohello",@test_string="hellohello",@test_string2="hellohello"; select @test_int,@test_double,@test_string,@test_string2; @test_int @test_double @test_string @test_string2 hellohello hellohello hellohello hellohello set @test_int=null,@test_double=null,@test_string=null,@test_string2=null; select @test_int,@test_double,@test_string,@test_string2; @test_int @test_double @test_string @test_string2 NULL NULL NULL NULL select @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3; @t1:=(@t2:=1)+@t3:=4 @t1 @t2 @t3 5 5 1 4 explain extended select @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used Warnings: Note 1003 select (@t1:=((@t2:=1) + (@t3:=4))) AS `@t1:=(@t2:=1)+@t3:=4`,(@t1) AS `@t1`,(@t2) AS `@t2`,(@t3) AS `@t3` select @t5; @t5 1.23456 CREATE TABLE t1 (c_id INT(4) NOT NULL, c_name CHAR(20), c_country CHAR(3), PRIMARY KEY(c_id)); INSERT INTO t1 VALUES (1,'Bozo','USA'),(2,'Ronald','USA'),(3,'Kinko','IRE'),(4,'Mr. Floppy','GB'); SELECT @min_cid:=min(c_id), @max_cid:=max(c_id) from t1; @min_cid:=min(c_id) @max_cid:=max(c_id) 1 4 SELECT * FROM t1 WHERE c_id=@min_cid OR c_id=@max_cid; c_id c_name c_country 1 Bozo USA 4 Mr. Floppy GB SELECT * FROM t1 WHERE c_id=@min_cid OR c_id=@max_cid OR c_id=666; c_id c_name c_country 1 Bozo USA 4 Mr. Floppy GB ALTER TABLE t1 DROP PRIMARY KEY; select * from t1 where c_id=@min_cid OR c_id=@max_cid; c_id c_name c_country 1 Bozo USA 4 Mr. Floppy GB drop table t1; set GLOBAL max_join_size=10; set max_join_size=100; show variables like 'max_join_size'; Variable_name Value max_join_size 100 select * from information_schema.session_variables where variable_name like 'max_join_size'; VARIABLE_NAME VARIABLE_VALUE MAX_JOIN_SIZE 100 show global variables like 'max_join_size'; Variable_name Value max_join_size 10 select * from information_schema.global_variables where variable_name like 'max_join_size'; VARIABLE_NAME VARIABLE_VALUE MAX_JOIN_SIZE 10 set GLOBAL max_join_size=2000; show global variables like 'max_join_size'; Variable_name Value max_join_size 2000 select * from information_schema.global_variables where variable_name like 'max_join_size'; VARIABLE_NAME VARIABLE_VALUE MAX_JOIN_SIZE 2000 set max_join_size=DEFAULT; show variables like 'max_join_size'; Variable_name Value max_join_size 2000 select * from information_schema.session_variables where variable_name like 'max_join_size'; VARIABLE_NAME VARIABLE_VALUE MAX_JOIN_SIZE 2000 set GLOBAL max_join_size=DEFAULT; show global variables like 'max_join_size'; Variable_name Value max_join_size HA_POS_ERROR select * from information_schema.global_variables where variable_name like 'max_join_size'; VARIABLE_NAME VARIABLE_VALUE MAX_JOIN_SIZE HA_POS_ERROR set @@max_join_size=1000, @@global.max_join_size=2000; select @@local.max_join_size, @@global.max_join_size; @@local.max_join_size @@global.max_join_size 1000 2000 select @@identity, length(@@version)>0; @@identity length(@@version)>0 0 1 select @@VERSION=version(); @@VERSION=version() 1 select last_insert_id(345); last_insert_id(345) 345 explain extended select last_insert_id(345); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used Warnings: Note 1003 select last_insert_id(345) AS `last_insert_id(345)` select @@IDENTITY,last_insert_id(), @@identity; @@IDENTITY last_insert_id() @@identity 345 345 345 explain extended select @@IDENTITY,last_insert_id(), @@identity; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL No tables used Warnings: Note 1003 select 345 AS `@@IDENTITY`,last_insert_id() AS `last_insert_id()`,345 AS `@@identity` set big_tables=OFF, big_tables=ON, big_tables=0, big_tables=1, big_tables="OFF", big_tables="ON"; set global concurrent_insert=2; show variables like 'concurrent_insert'; Variable_name Value concurrent_insert 2 select * from information_schema.session_variables where variable_name like 'concurrent_insert'; VARIABLE_NAME VARIABLE_VALUE CONCURRENT_INSERT 2 set global concurrent_insert=1; show variables like 'concurrent_insert'; Variable_name Value concurrent_insert 1 select * from information_schema.session_variables where variable_name like 'concurrent_insert'; VARIABLE_NAME VARIABLE_VALUE CONCURRENT_INSERT 1 set global concurrent_insert=0; show variables like 'concurrent_insert'; Variable_name Value concurrent_insert 0 select * from information_schema.session_variables where variable_name like 'concurrent_insert'; VARIABLE_NAME VARIABLE_VALUE CONCURRENT_INSERT 0 set global concurrent_insert=DEFAULT; select @@concurrent_insert; @@concurrent_insert 1 set global timed_mutexes=ON; show variables like 'timed_mutexes'; Variable_name Value timed_mutexes ON select * from information_schema.session_variables where variable_name like 'timed_mutexes'; VARIABLE_NAME VARIABLE_VALUE TIMED_MUTEXES ON set global timed_mutexes=0; show variables like 'timed_mutexes'; Variable_name Value timed_mutexes OFF select * from information_schema.session_variables where variable_name like 'timed_mutexes'; VARIABLE_NAME VARIABLE_VALUE TIMED_MUTEXES OFF set storage_engine=MYISAM, storage_engine="HEAP", global storage_engine="MERGE"; show local variables like 'storage_engine'; Variable_name Value storage_engine MEMORY select * from information_schema.session_variables where variable_name like 'storage_engine'; VARIABLE_NAME VARIABLE_VALUE STORAGE_ENGINE MEMORY show global variables like 'storage_engine'; Variable_name Value storage_engine MRG_MYISAM select * from information_schema.global_variables where variable_name like 'storage_engine'; VARIABLE_NAME VARIABLE_VALUE STORAGE_ENGINE MRG_MYISAM set GLOBAL query_cache_size=100000; set GLOBAL myisam_max_sort_file_size=2000000; show global variables like 'myisam_max_sort_file_size'; Variable_name Value myisam_max_sort_file_size 1048576 select * from information_schema.global_variables where variable_name like 'myisam_max_sort_file_size'; VARIABLE_NAME VARIABLE_VALUE MYISAM_MAX_SORT_FILE_SIZE 1048576 set GLOBAL myisam_max_sort_file_size=default; show variables like 'myisam_max_sort_file_size'; Variable_name Value myisam_max_sort_file_size FILE_SIZE select * from information_schema.session_variables where variable_name like 'myisam_max_sort_file_size'; VARIABLE_NAME VARIABLE_VALUE MYISAM_MAX_SORT_FILE_SIZE FILE_SIZE set global net_retry_count=10, session net_retry_count=10; set global net_buffer_length=1024, net_write_timeout=200, net_read_timeout=300; set session net_buffer_length=2048, net_write_timeout=500, net_read_timeout=600; show global variables like 'net_%'; Variable_name Value net_buffer_length 1024 net_read_timeout 300 net_retry_count 10 net_write_timeout 200 select * from information_schema.global_variables where variable_name like 'net_%' order by 1; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 1024 NET_READ_TIMEOUT 300 NET_RETRY_COUNT 10 NET_WRITE_TIMEOUT 200 show session variables like 'net_%'; Variable_name Value net_buffer_length 2048 net_read_timeout 600 net_retry_count 10 net_write_timeout 500 select * from information_schema.session_variables where variable_name like 'net_%' order by 1; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 2048 NET_READ_TIMEOUT 600 NET_RETRY_COUNT 10 NET_WRITE_TIMEOUT 500 set session net_buffer_length=8000, global net_read_timeout=900, net_write_timeout=1000; show global variables like 'net_%'; Variable_name Value net_buffer_length 1024 net_read_timeout 900 net_retry_count 10 net_write_timeout 1000 select * from information_schema.global_variables where variable_name like 'net_%' order by 1; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 1024 NET_READ_TIMEOUT 900 NET_RETRY_COUNT 10 NET_WRITE_TIMEOUT 1000 show session variables like 'net_%'; Variable_name Value net_buffer_length 7168 net_read_timeout 600 net_retry_count 10 net_write_timeout 500 select * from information_schema.session_variables where variable_name like 'net_%' order by 1; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 7168 NET_READ_TIMEOUT 600 NET_RETRY_COUNT 10 NET_WRITE_TIMEOUT 500 set net_buffer_length=1; Warnings: Warning 1292 Truncated incorrect net_buffer_length value: '1' show variables like 'net_buffer_length'; Variable_name Value net_buffer_length 1024 select * from information_schema.session_variables where variable_name like 'net_buffer_length'; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 1024 set net_buffer_length=2000000000; Warnings: Warning 1292 Truncated incorrect net_buffer_length value: '2000000000' show variables like 'net_buffer_length'; Variable_name Value net_buffer_length 1048576 select * from information_schema.session_variables where variable_name like 'net_buffer_length'; VARIABLE_NAME VARIABLE_VALUE NET_BUFFER_LENGTH 1048576 set character set cp1251_koi8; show variables like "character_set_client"; Variable_name Value character_set_client cp1251 select * from information_schema.session_variables where variable_name like 'character_set_client'; VARIABLE_NAME VARIABLE_VALUE CHARACTER_SET_CLIENT cp1251 select @@timestamp>0; @@timestamp>0 1 set @@rand_seed1=10000000,@@rand_seed2=1000000; select ROUND(RAND(),5); ROUND(RAND(),5) 0.02887 show variables like '%alloc%'; Variable_name Value query_alloc_block_size 8192 query_prealloc_size 8192 range_alloc_block_size 4096 transaction_alloc_block_size 8192 transaction_prealloc_size 4096 select * from information_schema.session_variables where variable_name like '%alloc%' order by 1; VARIABLE_NAME VARIABLE_VALUE QUERY_ALLOC_BLOCK_SIZE 8192 QUERY_PREALLOC_SIZE 8192 RANGE_ALLOC_BLOCK_SIZE 4096 TRANSACTION_ALLOC_BLOCK_SIZE 8192 TRANSACTION_PREALLOC_SIZE 4096 set @@range_alloc_block_size=1024*16; set @@query_alloc_block_size=1024*17+2; set @@query_prealloc_size=1024*18; set @@transaction_alloc_block_size=1024*20-1; set @@transaction_prealloc_size=1024*21-1; select @@query_alloc_block_size; @@query_alloc_block_size 17408 show variables like '%alloc%'; Variable_name Value query_alloc_block_size 17408 query_prealloc_size 18432 range_alloc_block_size 16384 transaction_alloc_block_size 19456 transaction_prealloc_size 20480 select * from information_schema.session_variables where variable_name like '%alloc%' order by 1; VARIABLE_NAME VARIABLE_VALUE QUERY_ALLOC_BLOCK_SIZE 17408 QUERY_PREALLOC_SIZE 18432 RANGE_ALLOC_BLOCK_SIZE 16384 TRANSACTION_ALLOC_BLOCK_SIZE 19456 TRANSACTION_PREALLOC_SIZE 20480 set @@range_alloc_block_size=default; set @@query_alloc_block_size=default, @@query_prealloc_size=default; set transaction_alloc_block_size=default, @@transaction_prealloc_size=default; show variables like '%alloc%'; Variable_name Value query_alloc_block_size 8192 query_prealloc_size 8192 range_alloc_block_size 4096 transaction_alloc_block_size 8192 transaction_prealloc_size 4096 select * from information_schema.session_variables where variable_name like '%alloc%' order by 1; VARIABLE_NAME VARIABLE_VALUE QUERY_ALLOC_BLOCK_SIZE 8192 QUERY_PREALLOC_SIZE 8192 RANGE_ALLOC_BLOCK_SIZE 4096 TRANSACTION_ALLOC_BLOCK_SIZE 8192 TRANSACTION_PREALLOC_SIZE 4096 SELECT @@version LIKE 'non-existent'; @@version LIKE 'non-existent' 0 SELECT @@version_compile_os LIKE 'non-existent'; @@version_compile_os LIKE 'non-existent' 0 set big_tables=OFFF; ERROR 42000: Variable 'big_tables' can't be set to the value of 'OFFF' set big_tables="OFFF"; ERROR 42000: Variable 'big_tables' can't be set to the value of 'OFFF' set unknown_variable=1; ERROR HY000: Unknown system variable 'unknown_variable' set max_join_size="hello"; ERROR 42000: Incorrect argument type to variable 'max_join_size' set storage_engine=UNKNOWN_TABLE_TYPE; ERROR 42000: Unknown table engine 'UNKNOWN_TABLE_TYPE' set storage_engine=MERGE, big_tables=2; ERROR 42000: Variable 'big_tables' can't be set to the value of '2' show local variables like 'storage_engine'; Variable_name Value storage_engine MEMORY set SESSION query_cache_size=10000; ERROR HY000: Variable 'query_cache_size' is a GLOBAL variable and should be set with SET GLOBAL set GLOBAL storage_engine=DEFAULT; ERROR 42000: Variable 'storage_engine' doesn't have a default value set character_set_client=UNKNOWN_CHARACTER_SET; ERROR 42000: Unknown character set: 'UNKNOWN_CHARACTER_SET' set collation_connection=UNKNOWN_COLLATION; ERROR HY000: Unknown collation: 'UNKNOWN_COLLATION' set character_set_client=NULL; ERROR 42000: Variable 'character_set_client' can't be set to the value of 'NULL' set collation_connection=NULL; ERROR 42000: Variable 'collation_connection' can't be set to the value of 'NULL' set global autocommit=1; ERROR HY000: Variable 'autocommit' is a SESSION variable and can't be used with SET GLOBAL select @@global.timestamp; ERROR HY000: Variable 'timestamp' is a SESSION variable set @@version=''; ERROR HY000: Variable 'version' is a read only variable set @@concurrent_insert=1; ERROR HY000: Variable 'concurrent_insert' is a GLOBAL variable and should be set with SET GLOBAL set @@global.sql_auto_is_null=1; ERROR HY000: Variable 'sql_auto_is_null' is a SESSION variable and can't be used with SET GLOBAL select @@global.sql_auto_is_null; ERROR HY000: Variable 'sql_auto_is_null' is a SESSION variable set myisam_max_sort_file_size=100; ERROR HY000: Variable 'myisam_max_sort_file_size' is a GLOBAL variable and should be set with SET GLOBAL set @@SQL_WARNINGS=NULL; ERROR 42000: Variable 'sql_warnings' can't be set to the value of 'NULL' set autocommit=1; set big_tables=1; select @@autocommit, @@big_tables; @@autocommit @@big_tables 1 1 set global binlog_cache_size=100; Warnings: Warning 1292 Truncated incorrect binlog_cache_size value: '100' set bulk_insert_buffer_size=100; set character set cp1251_koi8; set character set default; set @@global.concurrent_insert=1; set global connect_timeout=100; select @@delay_key_write; @@delay_key_write ON set global delay_key_write="OFF"; select @@delay_key_write; @@delay_key_write OFF set global delay_key_write=ALL; select @@delay_key_write; @@delay_key_write ALL set global delay_key_write=1; select @@delay_key_write; @@delay_key_write ON set global delayed_insert_limit=100; set global delayed_insert_timeout=100; set global delayed_queue_size=100; set global flush=1; set global flush_time=100; set insert_id=1; set interactive_timeout=100; set join_buffer_size=100; Warnings: Warning 1292 Truncated incorrect join_buffer_size value: '100' set last_insert_id=1; set global local_infile=1; set long_query_time=0.000001; select @@long_query_time; @@long_query_time 0.000001 set long_query_time=100.000001; select @@long_query_time; @@long_query_time 100.000001 set low_priority_updates=1; set max_allowed_packet=100; Warnings: Warning 1292 Truncated incorrect max_allowed_packet value: '100' set global max_binlog_cache_size=100; Warnings: Warning 1292 Truncated incorrect max_binlog_cache_size value: '100' set global max_binlog_size=100; Warnings: Warning 1292 Truncated incorrect max_binlog_size value: '100' set global max_connect_errors=100; set global max_connections=100; set global max_delayed_threads=100; set max_heap_table_size=100; Warnings: Warning 1292 Truncated incorrect max_heap_table_size value: '100' set max_join_size=100; set max_sort_length=100; set max_tmp_tables=100; set global max_user_connections=100; select @@max_user_connections; @@max_user_connections 100 set global max_write_lock_count=100; set myisam_sort_buffer_size=100; set net_buffer_length=100; Warnings: Warning 1292 Truncated incorrect net_buffer_length value: '100' set net_read_timeout=100; set net_write_timeout=100; set global query_cache_limit=100; set global query_cache_size=100; set global query_cache_type=demand; set read_buffer_size=100; Warnings: Warning 1292 Truncated incorrect read_buffer_size value: '100' set read_rnd_buffer_size=100; Warnings: Warning 1292 Truncated incorrect read_rnd_buffer_size value: '100' set global rpl_recovery_rank=100; set global server_id=100; set global slow_launch_time=100; set sort_buffer_size=100; Warnings: Warning 1292 Truncated incorrect sort_buffer_size value: '100' set @@max_sp_recursion_depth=10; select @@max_sp_recursion_depth; @@max_sp_recursion_depth 10 set @@max_sp_recursion_depth=0; select @@max_sp_recursion_depth; @@max_sp_recursion_depth 0 set sql_auto_is_null=1; select @@sql_auto_is_null; @@sql_auto_is_null 1 set @@sql_auto_is_null=0; select @@sql_auto_is_null; @@sql_auto_is_null 0 set sql_big_selects=1; set sql_big_tables=1; set sql_buffer_result=1; set sql_log_bin=1; set sql_log_off=1; set sql_log_update=1; Warnings: Note 1315 The update log is deprecated and replaced by the binary log; SET SQL_LOG_UPDATE has been ignored set sql_low_priority_updates=1; set sql_max_join_size=200; select @@sql_max_join_size,@@max_join_size; @@sql_max_join_size @@max_join_size 200 200 set sql_quote_show_create=1; set sql_safe_updates=1; set sql_select_limit=1; set sql_select_limit=default; set sql_warnings=1; set global table_open_cache=100; set storage_engine=myisam; set global thread_cache_size=100; set timestamp=1, timestamp=default; set tmp_table_size=100; Warnings: Warning 1292 Truncated incorrect tmp_table_size value: '100' set tx_isolation="READ-COMMITTED"; set wait_timeout=100; set log_warnings=1; set global log_warnings=1; select @@session.insert_id; @@session.insert_id 1 set @save_insert_id=@@session.insert_id; set session insert_id=20; select @@session.insert_id; @@session.insert_id 20 set session last_insert_id=100; select @@session.insert_id; @@session.insert_id 20 select @@session.last_insert_id; @@session.last_insert_id 100 select @@session.insert_id; @@session.insert_id 20 set @@session.insert_id=@save_insert_id; select @@session.insert_id; @@session.insert_id 1 create table t1 (a int not null auto_increment, primary key(a)); create table t2 (a int not null auto_increment, primary key(a)); insert into t1 values(null),(null),(null); insert into t2 values(null),(null),(null); set global key_buffer_size=100000; select @@key_buffer_size; @@key_buffer_size 98304 select * from t1 where a=2; a 2 select * from t2 where a=3; a 3 check table t1,t2; Table Op Msg_type Msg_text test.t1 check status OK test.t2 check status OK select max(a) +1, max(a) +2 into @xx,@yy from t1; drop table t1,t2; select @@xxxxxxxxxx; ERROR HY000: Unknown system variable 'xxxxxxxxxx' select 1; 1 1 select @@session.key_buffer_size; ERROR HY000: Variable 'key_buffer_size' is a GLOBAL variable set ft_boolean_syntax = @@init_connect; ERROR HY000: Variable 'ft_boolean_syntax' is a GLOBAL variable and should be set with SET GLOBAL set global ft_boolean_syntax = @@init_connect; ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of '' set init_connect = NULL; ERROR HY000: Variable 'init_connect' is a GLOBAL variable and should be set with SET GLOBAL set global init_connect = NULL; set ft_boolean_syntax = @@init_connect; ERROR HY000: Variable 'ft_boolean_syntax' is a GLOBAL variable and should be set with SET GLOBAL set global ft_boolean_syntax = @@init_connect; ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of '' set global myisam_max_sort_file_size=4294967296; show global variables like 'myisam_max_sort_file_size'; Variable_name Value myisam_max_sort_file_size MAX_FILE_SIZE select * from information_schema.global_variables where variable_name like 'myisam_max_sort_file_size'; VARIABLE_NAME VARIABLE_VALUE MYISAM_MAX_SORT_FILE_SIZE MAX_FILE_SIZE set global myisam_max_sort_file_size=default; select @@global.max_user_connections,@@local.max_join_size; @@global.max_user_connections @@local.max_join_size 100 200 set @svc=@@global.max_user_connections, @svj=@@local.max_join_size; select @@global.max_user_connections,@@local.max_join_size; @@global.max_user_connections @@local.max_join_size 100 200 set @@global.max_user_connections=111,@@local.max_join_size=222; select @@global.max_user_connections,@@local.max_join_size; @@global.max_user_connections @@local.max_join_size 111 222 set @@global.max_user_connections=@@local.max_join_size,@@local.max_join_size=@@global.max_user_connections; select @@global.max_user_connections,@@local.max_join_size; @@global.max_user_connections @@local.max_join_size 222 111 set @@global.max_user_connections=@svc, @@local.max_join_size=@svj; select @@global.max_user_connections,@@local.max_join_size; @@global.max_user_connections @@local.max_join_size 100 200 set @a=1, @b=2; set @a=@b, @b=@a; select @a, @b; @a @b 2 1 set @@global.global.key_buffer_size= 1; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key_buffer_size= 1' at line 1 set GLOBAL global.key_buffer_size= 1; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key_buffer_size= 1' at line 1 SELECT @@global.global.key_buffer_size; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key_buffer_size' at line 1 SELECT @@global.session.key_buffer_size; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key_buffer_size' at line 1 SELECT @@global.local.key_buffer_size; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key_buffer_size' at line 1 set @tstlw = @@log_warnings; show global variables like 'log_warnings'; Variable_name Value log_warnings 1 select * from information_schema.global_variables where variable_name like 'log_warnings'; VARIABLE_NAME VARIABLE_VALUE LOG_WARNINGS 1 set global log_warnings = 0; show global variables like 'log_warnings'; Variable_name Value log_warnings 0 select * from information_schema.global_variables where variable_name like 'log_warnings'; VARIABLE_NAME VARIABLE_VALUE LOG_WARNINGS 0 set global log_warnings = 42; show global variables like 'log_warnings'; Variable_name Value log_warnings 42 select * from information_schema.global_variables where variable_name like 'log_warnings'; VARIABLE_NAME VARIABLE_VALUE LOG_WARNINGS 42 set global log_warnings = @tstlw; show global variables like 'log_warnings'; Variable_name Value log_warnings 1 select * from information_schema.global_variables where variable_name like 'log_warnings'; VARIABLE_NAME VARIABLE_VALUE LOG_WARNINGS 1 create table t1 ( c1 tinyint, c2 smallint, c3 mediumint, c4 int, c5 bigint); show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `c1` tinyint(4) DEFAULT NULL, `c2` smallint(6) DEFAULT NULL, `c3` mediumint(9) DEFAULT NULL, `c4` int(11) DEFAULT NULL, `c5` bigint(20) DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 drop table t1; set @arg00= 8, @arg01= 8.8, @arg02= 'a string', @arg03= 0.2e0; create table t1 as select @arg00 as c1, @arg01 as c2, @arg02 as c3, @arg03 as c4; show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `c1` bigint(20) DEFAULT NULL, `c2` decimal(65,30) DEFAULT NULL, `c3` longtext, `c4` double DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 drop table t1; SET GLOBAL MYISAM_DATA_POINTER_SIZE= 7; SHOW VARIABLES LIKE 'MYISAM_DATA_POINTER_SIZE'; Variable_name Value myisam_data_pointer_size 7 SELECT * FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME LIKE 'MYISAM_DATA_POINTER_SIZE'; VARIABLE_NAME VARIABLE_VALUE MYISAM_DATA_POINTER_SIZE 7 SET GLOBAL table_open_cache=-1; Warnings: Warning 1292 Truncated incorrect table_open_cache value: '0' SHOW VARIABLES LIKE 'table_open_cache'; Variable_name Value table_open_cache 1 SELECT * FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME LIKE 'table_open_cache'; VARIABLE_NAME VARIABLE_VALUE TABLE_OPEN_CACHE 1 SET GLOBAL table_open_cache=DEFAULT; set character_set_results=NULL; select ifnull(@@character_set_results,"really null"); ifnull(@@character_set_results,"really null") really null set names latin1; select @@have_innodb; @@have_innodb # *** Various tests with LC_TIME_NAMES *** LC_TIME_NAMES: testing case insensitivity set @@lc_time_names='ru_ru'; select @@lc_time_names; @@lc_time_names ru_RU *** LC_TIME_NAMES: testing with a user variable set @lc='JA_JP'; set @@lc_time_names=@lc; select @@lc_time_names; @@lc_time_names ja_JP *** LC_TIME_NAMES: testing with string expressions set lc_time_names=concat('de','_','DE'); select @@lc_time_names; @@lc_time_names de_DE set lc_time_names=concat('de','+','DE'); ERROR HY000: Unknown locale: 'de+DE' select @@lc_time_names; @@lc_time_names de_DE LC_TIME_NAMES: testing with numeric expressions set @@lc_time_names=1+2; select @@lc_time_names; @@lc_time_names sv_SE set @@lc_time_names=1/0; ERROR 42000: Incorrect argument type to variable 'lc_time_names' select @@lc_time_names; @@lc_time_names sv_SE set lc_time_names=en_US; LC_TIME_NAMES: testing NULL and a negative number: set lc_time_names=NULL; ERROR 42000: Variable 'lc_time_names' can't be set to the value of 'NULL' set lc_time_names=-1; ERROR HY000: Unknown locale: '-1' select @@lc_time_names; @@lc_time_names en_US LC_TIME_NAMES: testing locale with the last ID: set lc_time_names=108; select @@lc_time_names; @@lc_time_names zh_HK LC_TIME_NAMES: testing a number beyond the valid ID range: set lc_time_names=109; ERROR HY000: Unknown locale: '109' select @@lc_time_names; @@lc_time_names zh_HK LC_TIME_NAMES: testing that 0 is en_US: set lc_time_names=0; select @@lc_time_names; @@lc_time_names en_US select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names en_US en_US set @@global.lc_time_names=fr_FR; select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names fr_FR en_US New connection select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names fr_FR fr_FR set @@lc_time_names=ru_RU; select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names fr_FR ru_RU Returnung to default connection select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names fr_FR en_US set lc_time_names=default; select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names fr_FR fr_FR set @@global.lc_time_names=default; select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names en_US fr_FR set @@lc_time_names=default; select @@global.lc_time_names, @@lc_time_names; @@global.lc_time_names @@lc_time_names en_US en_US set @test = @@query_prealloc_size; set @@query_prealloc_size = @test; select @@query_prealloc_size = @test; @@query_prealloc_size = @test 1 set global sql_mode=repeat('a',80); ERROR 42000: Variable 'sql_mode' can't be set to the value of 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa' End of 4.1 tests create table t1 (a int); select a into @x from t1; Warnings: Warning 1329 No data - zero rows fetched, selected, or processed show warnings; Level Code Message Warning 1329 No data - zero rows fetched, selected, or processed drop table t1; set @@warning_count=1; ERROR HY000: Variable 'warning_count' is a read only variable set @@global.error_count=1; ERROR HY000: Variable 'error_count' is a read only variable set @@max_heap_table_size= 4294967296; select @@max_heap_table_size > 0; @@max_heap_table_size > 0 1 set global max_heap_table_size= 4294967296; select @@max_heap_table_size > 0; @@max_heap_table_size > 0 1 set @@max_heap_table_size= 4294967296; select @@max_heap_table_size > 0; @@max_heap_table_size > 0 1 select @@character_set_system; @@character_set_system utf8 set global character_set_system = latin1; ERROR HY000: Variable 'character_set_system' is a read only variable set @@global.version_compile_os='234'; ERROR HY000: Variable 'version_compile_os' is a read only variable set character_set_filesystem=latin1; select @@character_set_filesystem; @@character_set_filesystem latin1 set @@global.character_set_filesystem=latin2; set character_set_filesystem=latin1; select @@character_set_filesystem; @@character_set_filesystem latin1 set @@global.character_set_filesystem=latin2; set character_set_filesystem=default; select @@character_set_filesystem; @@character_set_filesystem latin2 set @@global.character_set_filesystem=default; select @@global.character_set_filesystem; @@global.character_set_filesystem binary set @old_sql_big_selects = @@sql_big_selects; set @@sql_big_selects = 1; show variables like 'sql_big_selects'; Variable_name Value sql_big_selects ON select * from information_schema.session_variables where variable_name like 'sql_big_selects'; VARIABLE_NAME VARIABLE_VALUE SQL_BIG_SELECTS ON set @@sql_big_selects = @old_sql_big_selects; set @@sql_notes = 0, @@sql_warnings = 0; show variables like 'sql_notes'; Variable_name Value sql_notes OFF select * from information_schema.session_variables where variable_name like 'sql_notes'; VARIABLE_NAME VARIABLE_VALUE SQL_NOTES OFF show variables like 'sql_warnings'; Variable_name Value sql_warnings OFF select * from information_schema.session_variables where variable_name like 'sql_warnings'; VARIABLE_NAME VARIABLE_VALUE SQL_WARNINGS OFF set @@sql_notes = 1, @@sql_warnings = 1; show variables like 'sql_notes'; Variable_name Value sql_notes ON select * from information_schema.session_variables where variable_name like 'sql_notes'; VARIABLE_NAME VARIABLE_VALUE SQL_NOTES ON show variables like 'sql_warnings'; Variable_name Value sql_warnings ON select * from information_schema.session_variables where variable_name like 'sql_warnings'; VARIABLE_NAME VARIABLE_VALUE SQL_WARNINGS ON select @@system_time_zone; @@system_time_zone # select @@version, @@version_comment, @@version_compile_machine, @@version_compile_os; @@version @@version_comment @@version_compile_machine @@version_compile_os # # # # select @@basedir, @@datadir, @@tmpdir; @@basedir @@datadir @@tmpdir # # # show variables like 'basedir'; Variable_name Value basedir # select * from information_schema.session_variables where variable_name like 'basedir'; VARIABLE_NAME VARIABLE_VALUE BASEDIR # show variables like 'datadir'; Variable_name Value datadir # select * from information_schema.session_variables where variable_name like 'datadir'; VARIABLE_NAME VARIABLE_VALUE DATADIR # show variables like 'tmpdir'; Variable_name Value tmpdir # select * from information_schema.session_variables where variable_name like 'tmpdir'; VARIABLE_NAME VARIABLE_VALUE TMPDIR # select @@ssl_ca, @@ssl_capath, @@ssl_cert, @@ssl_cipher, @@ssl_key; @@ssl_ca @@ssl_capath @@ssl_cert @@ssl_cipher @@ssl_key # # # # # show variables like 'ssl%'; Variable_name Value ssl_ca # ssl_capath # ssl_cert # ssl_cipher # ssl_key # select * from information_schema.session_variables where variable_name like 'ssl%' order by 1; VARIABLE_NAME VARIABLE_VALUE SSL_CA # SSL_CAPATH # SSL_CERT # SSL_CIPHER # SSL_KEY # select @@log_queries_not_using_indexes; @@log_queries_not_using_indexes 0 show variables like 'log_queries_not_using_indexes'; Variable_name Value log_queries_not_using_indexes OFF select * from information_schema.session_variables where variable_name like 'log_queries_not_using_indexes'; VARIABLE_NAME VARIABLE_VALUE LOG_QUERIES_NOT_USING_INDEXES OFF select @@""; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '""' at line 1 select @@&; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '&' at line 1 select @@@; ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@' at line 1 select @@hostname; @@hostname # set @@hostname= "anothername"; ERROR HY000: Variable 'hostname' is a read only variable show variables like 'hostname'; Variable_name Value hostname # End of 5.0 tests set global binlog_cache_size =@my_binlog_cache_size; set global connect_timeout =@my_connect_timeout; set global delayed_insert_timeout =@my_delayed_insert_timeout; set global delayed_queue_size =@my_delayed_queue_size; set global flush =@my_flush; set global flush_time =@my_flush_time; set global key_buffer_size =@my_key_buffer_size; set global max_binlog_cache_size =default; set global max_binlog_size =@my_max_binlog_size; set global max_connect_errors =@my_max_connect_errors; set global max_connections =@my_max_connections; set global max_delayed_threads =@my_max_delayed_threads; set global max_heap_table_size =@my_max_heap_table_size; set global max_insert_delayed_threads=@my_max_insert_delayed_threads; set global max_join_size =@my_max_join_size; set global max_user_connections =default; set global max_write_lock_count =default; set global myisam_data_pointer_size =@my_myisam_data_pointer_size; set global net_buffer_length =@my_net_buffer_length; set global net_write_timeout =@my_net_write_timeout; set global net_read_timeout =@my_net_read_timeout; set global query_cache_limit =@my_query_cache_limit; set global query_cache_type =@my_query_cache_type; set global rpl_recovery_rank =@my_rpl_recovery_rank; set global server_id =@my_server_id; set global slow_launch_time =@my_slow_launch_time; set global storage_engine =@my_storage_engine; set global thread_cache_size =@my_thread_cache_size; show global variables where Variable_name='table_definition_cache' or Variable_name='table_lock_wait_timeout'; Variable_name Value table_definition_cache # table_lock_wait_timeout #