# 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/centralized-devg-v3-gaussdb/gaussdb-42-0254.html#ZH-CN_TOPIC_0000002235458857)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：
```
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
int main(void) 
{ 
    EXEC SQL CONNECT TO testdb AS con1; 
    EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT; 
    EXEC SQL ALLOCATE DESCRIPTOR d; 
    EXEC SQL DECLARE cur CURSOR FOR SELECT current_database(), 'hoge', 256; 
    EXEC SQL OPEN cur; 
  
    /* 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 CLOSE cur; 
     EXEC SQL COMMIT; 
     EXEC SQL DEALLOCATE DESCRIPTOR d; 
     EXEC SQL DISCONNECT ALL; 
     return 0; 
}
```