SET Statements • SET PASSWORD  assigns account passwords. See Section 13.7.1.10, “SET PASSWORD Statement” . • SET RESOURCE GROUP  assigns threads to a resource group. See Section 13.7.2.4, “SET RESOURCE GROUP Statement” . • SET TRANSACTION ISOLATION LEVEL  sets the isolation level for transaction processing. See Section 13.3.7, “SET TRANSACTION Statement” . 13.7.6.1 SET Syntax for Variable Assignment SET  variable  =  expr  [,  variable  =  expr ] ... variable : { user_var_name |  param_name |  local_var_name | {GLOBAL | @@GLOBAL.}  system_var_name | {PERSIST | @@PERSIST.}  system_var_name | {PERSIST_ONLY | @@PERSIST_ONLY.}  system_var_name | [SESSION | @@SESSION. | @@]  system_var_name } SET  syntax for variable assignment enables you to assign values to different types of variables that affect the operation of the server or clients: A  SET  statement that assigns variable values is not written to the binary log, so in replication scenarios it affects only the host on which you execute it. To affect all replication hosts, execute the statement on each host. The following sections describe  SET  syntax for setting variables. They use the  =  assignment operator, but the  :=  assignment operator is also permitted for this purpose. User-defined variables are created locally within a session and exist only within the context of that session; see Section 9.4, “User-Defined Variables” . A user-defined variable is written as  @ var_name  and is assigned an expression value as follows: 2906 User-Defined Variable Assignment •System Variable References in Expressions •Multiple Variable Assignment •SET Error Handling •System Variable Assignment •Parameter and Local Variable Assignment •User-Defined Variable Assignment •System variables. See Section 5.1.8, “Server System Variables” . System variables also can be set at server startup, as described in Section 5.1.9, “Using System Variables” . •Stored procedure and function parameters, and stored program local variables. See Section 13.6.4, “Variables in Stored Programs” . •User-defined variables. See Section 9.4, “User-Defined Variables” . SET @ var_name  =  expr ;