New syntax to change client collation:

SET COLLATION latin1
SET COLLATION 'latin1'
SET COLLATION DEFAULT

mysql-test/r/ctype_collate.result

@@ -511,16 +511,55 @@ SHOW FIELDS FROM  t1;
 Field	Type	Collation	Null	Key	Default	Extra
 latin1_f	char(32)	latin1_bin	YES		NULL	
 SET NAMES 'latin1';
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1
 SET NAMES latin1;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
 latin1	latin1	2	1
 SET NAMES latin1 COLLATE latin1_bin;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1_bin
 SET NAMES 'latin1' COLLATE 'latin1_bin';
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1_bin
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
 latin1	latin1_bin	2	0
+SET NAMES koi8r;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	koi8r
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+charset('a')	collation('a')	coercibility('a')	'a'='A'
+koi8r	koi8r	2	1
+SET COLLATION koi8r_bin;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	koi8r_bin
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+charset('a')	collation('a')	coercibility('a')	'a'='A'
+koi8r	koi8r_bin	2	0
+SET COLLATION DEFAULT;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	koi8r
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+charset('a')	collation('a')	coercibility('a')	'a'='A'
+koi8r	koi8r	2	1
 SET NAMES DEFAULT;
+SHOW VARIABLES LIKE 'client_collation';
+Variable_name	Value
+client_collation	latin1
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
 latin1	latin1	2	1

mysql-test/t/ctype_collate.test

@@ -128,12 +128,27 @@ SHOW CREATE TABLE t1;
 SHOW FIELDS FROM  t1;
 
 SET NAMES 'latin1';
+SHOW VARIABLES LIKE 'client_collation';
 SET NAMES latin1;
+SHOW VARIABLES LIKE 'client_collation';
+SHOW VARIABLES LIKE 'client_collation';
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 SET NAMES latin1 COLLATE latin1_bin;
+SHOW VARIABLES LIKE 'client_collation';
 SET NAMES 'latin1' COLLATE 'latin1_bin';
+SHOW VARIABLES LIKE 'client_collation';
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+SET NAMES koi8r;
+SHOW VARIABLES LIKE 'client_collation';
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+SET COLLATION koi8r_bin;
+SHOW VARIABLES LIKE 'client_collation';
+SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
+SET COLLATION DEFAULT;
+SHOW VARIABLES LIKE 'client_collation';
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 SET NAMES DEFAULT;
+SHOW VARIABLES LIKE 'client_collation';
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 --error 1251
 SET NAMES latin1 COLLATE koi8r;

sql/sql_yacc.yy

@@ -4224,7 +4224,6 @@ option_value:
 	{
 	  THD* thd= YYTHD;
 	  LEX *lex= &thd->lex;
-	  system_variables vars= thd->variables;
 	  CHARSET_INFO *cs= $2 ? $2 : thd->db_charset;
 	  CHARSET_INFO *cl= $3 ? $3 : cs;
 
@@ -4241,6 +4240,35 @@ option_value:
 					      find_sys_var("client_collation"),
 					      csname));
 	}
+	| COLLATION_SYM collation_name_or_default
+	{
+	  THD* thd= YYTHD;
+	  LEX *lex= &thd->lex;
+	  system_variables *vars= &thd->variables;
+	  CHARSET_INFO *cs= vars->thd_charset;
+	  CHARSET_INFO *cl= $2;
+
+	  if (!cl)
+	  {
+	    if (!(cl=get_charset_by_csname(cs->csname,MY_CS_PRIMARY,MYF(0))))
+	    {
+	      net_printf(YYTHD,ER_UNKNOWN_CHARACTER_SET,"DEFAULT");
+	      YYABORT;
+	    }
+	  }
+	  else if ((cl != cs) && strcmp(cs->csname,cl->csname))
+	  {
+	      net_printf(YYTHD,ER_COLLATION_CHARSET_MISMATCH, 
+		         cl->name,cs->csname);
+	      YYABORT;
+	  }
+	  Item_string *csname= new Item_string(cl->name, 
+					       strlen(cl->name), 
+					       &my_charset_latin1);
+	  lex->var_list.push_back(new set_var(lex->option_type,
+					      find_sys_var("client_collation"),
+					      csname));
+	}
 	| PASSWORD equal text_or_password
 	  {
 	    THD *thd=YYTHD;