# WHENEVER
#### 功能描述
定义一个行为，它会在SQL执行异常时（行未找到、SQL告警或错误）被调用。
#### 语法格式
```
WHENEVER { NOT FOUND | SQLERROR | SQLWARNING } action
```
#### 参数说明
参数描述请参见[设置回调](https://support.huaweicloud.com/distributed-devg-v8-gaussdb/gaussdb-12-0213.html#ZH-CN_TOPIC_0000002559105579)章节。
#### 示例
```
EXEC SQL WHENEVER NOT FOUND CONTINUE; 
EXEC SQL WHENEVER NOT FOUND DO BREAK; 
EXEC SQL WHENEVER SQLWARNING SQLPRINT; 
EXEC SQL WHENEVER SQLWARNING DO warn(); 
EXEC SQL WHENEVER SQLERROR sqlprint; 
EXEC SQL WHENEVER SQLERROR SQLCALL print2(); 
EXEC SQL WHENEVER SQLERROR DO handle_error("select"); 
EXEC SQL WHENEVER SQLERROR DO sqlnotice(NULL, NONO);
EXEC SQL WHENEVER SQLERROR DO sqlprint(); 
EXEC SQL WHENEVER SQLERROR GOTO error_label; 
EXEC SQL WHENEVER SQLERROR STOP;
```
使用WHENEVER NOT FOUND BREAK来处理结果集的循环，参考如下完整示例：
```
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(void)
{
    EXEC SQL CONNECT TO testdb AS con1;
    EXEC SQL ALLOCATE DESCRIPTOR d;
    EXEC SQL DECLARE cur CURSOR FOR SELECT current_database(), 'hoge', 256;
    EXEC SQL OPEN cur;
    EXEC SQL BEGIN DECLARE SECTION;
    char* d1;
    char* d2;
    EXEC SQL END DECLARE SECTION;
    /* 当到达结果集末尾时，跳出循环 */
    EXEC SQL WHENEVER NOT FOUND DO BREAK;
    while (1)
    {
        EXEC SQL FETCH NEXT FROM cur INTO SQL DESCRIPTOR d;
        exec sql get descriptor d value 1 :d1=DATA;
        exec sql get descriptor d value 2 :d2=DATA;
        printf("d1 is %s,%s\n", d1, d2) ;
    }
     EXEC SQL CLOSE cur;
     EXEC SQL COMMIT;
     EXEC SQL DEALLOCATE DESCRIPTOR d;
     EXEC SQL DISCONNECT ALL;
     return 0;
}
```