Question

我正在尝试在sqlite3中创建一个计数器

列c3是我的计数器

如果c1和c2与update语句不匹配，我需要的是一个插入新行的触发器。

设置：

CREATE TABLE t1 (c1,c2,c3);
INSERT INTO t1 VALUES (1,1,1);

我的更新命令：

UPDATE t1 SET c3=(SELECT c3 FROM t1 WHERE c1=1 AND c2=1) + 1 WHERE c1=1 AND c2=1;

这是触发器，我得到的但是它不起作用：

CREATE TRIGGER tr1 
BEFORE UPDATE ON t1 
  WHEN (SELECT COUNT(*) FROM t1 WHERE c1=NEW.c1 AND c2=NEW.c2) < 1 
    BEGIN 
      INSERT INTO t1 (c1,c2,c3) VALUES (NEW.c1, NEW.c2, 0); 
    END;

以下是我尝试的一些绝望的事情：

CREATE TRIGGER tr1 BEFORE UPDATE ON t1 WHEN (SELECT COUNT(*) FROM t1 WHERE c1=1 AND c2=2) < 1 BEGIN INSERT INTO t1 (c1,c2,c3) VALUES (2, 2, 0); END;
CREATE TRIGGER tr2 BEFORE UPDATE ON t1 WHEN (SELECT COUNT(*) FROM t1 WHERE c1=NEW.c1 AND c2=NEW.c2) = 0 BEGIN INSERT INTO t1 VALUES (2, 2, 0); END;
CREATE TRIGGER tr3 AFTER UPDATE ON t1 WHEN (SELECT COUNT(*) FROM t1 WHERE c1=NEW.c1 AND c2=NEW.c2) = 0 BEGIN INSERT INTO t1 VALUES (2, 2, 0); END;

Answer 1

使用insert和2个触发器。

创建表t1（c1，c2，c3）;

CREATE TRIGGER tr1 BEFORE INSERT ON t1 BEGIN SELECT RAISE(IGNORE) WHERE (SELECT COUNT(*) FROM t1 WHERE c1=NEW.c1 AND c2=NEW.c2) > 0;
END;
CREATE TRIGGER tr2 BEFORE INSERT ON t1 BEGIN UPDATE t1 SET c3=(SELECT c3 FROM t1 WHERE c1=NEW.c1 AND c2=NEW.c2) + 1 WHERE c1=new.c1 AND c2=new.c2;END;
COMMIT;

这将插入：

INSERT INTO t1 VALUES (1,1,1);

这将更新并递增计数器：

INSERT INTO t1 VALUES (1,1,1);

如果有人可以将这些触发器组合成一个很棒的触发器。

如果count（*）为0，则TRIGGER在UPDATE到INSERT行

1 个答案: