SET

Purpose

This statement is used to set variables.

Syntax

SET [SESSION | GLOBAL] var_and_val_list

var_and_val_list:
  var_and_val [,var_and_val ...]

var_and_val:
   var_value {TO | =} set_expr_or_default
 | var_value = (simple_select)

Parameters

Examples

1. Set the user variable a.

   obclient> SET @a = 1;
   

2. Set the global system variable secure_file_priv, which specifies the path for importing or exporting files.

   obclient> SET GLOBAL secure_file_priv = '';
   

3. Set the user variable proxy_route_policy, which is used to configure the routing policy.

   obclient> SET @proxy_route_policy = 'follower_first';
   

4. Set the variable value by using the SELECT statement.

   obclient> CREATE TABLE tbl1(col INT);
   obclient> INSERT into tbl1 VALUES('1'),('2'),('3'),('4'),('5');
   obclient> SET @var1=(SELECT COUNT(*) FROM tbl1);
   

   Query the variable value:

   obclient> SELECT @var1;
   

   The query result is as follows:

   +-------+
   | @var1 |
   +-------+
   |     5 |
   +-------+
   1 row in set