MySQL預存程序LOOP迴圈語句用法

MySQL預存程序的語句中有三個標準的迴圈方式：WHILE迴圈，LOOP迴圈以及REPEAT迴圈。還有一種非標準的迴圈方式：GOTO，不過這種迴圈方式最好別用，很容易引起程式的混亂，在這裡就不錯具體介紹了。

今天我們先來看看LOOP迴圈

mysql教程>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
    -> BEGIN
    ->
    ->     DECLARE i int;
    ->     SET i=0;
    ->     loop1: LOOP
    ->          SET i=i+1;
    ->          IF i>=10 THEN          /*Last number - exit loop*/
    ->               LEAVE loop1;
    ->          ELSEIF MOD(i,2)=0 THEN /*Even number - try again*/
    ->               ITERATE loop1;
    ->          END IF;
    ->
    ->          SELECT CONCAT(i," is an odd number");
    ->
    ->     END LOOP loop1;
    ->
    ->
    -> END$$
Query OK, 0 rows affected (0.02 sec)

mysql>
mysql> delimiter ;
mysql> call myProc();
+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 1 is an odd number            |
+-------------------------------+
1 row in set (0.00 sec)

+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 3 is an odd number            |
+-------------------------------+
1 row in set (0.00 sec)

+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 5 is an odd number            |
+-------------------------------+
1 row in set (0.00 sec)

+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 7 is an odd number            |
+-------------------------------+
1 row in set (0.01 sec)

+-------------------------------+
| CONCAT(i," is an odd number") |
+-------------------------------+
| 9 is an odd number            |
+-------------------------------+
1 row in set (0.01 sec)

Query OK, 0 rows affected (0.01 sec)

mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)

mysql>