如何比较 SQLite 中触发器内的 COUNT 结果?
到目前为止,这是我想出的代码:
CREATE TRIGGER mytrigger
BEFORE INSERT ON mytable
BEGIN
SELECT CASE WHEN
SELECT COUNT (*) FROM mytable >= 3
THEN
RAISE(FAIL, "Activated - mytrigger.")
END;
END;
它无法编译:
Error: near "SELECT": syntax error
如果我更换SELECT COUNT (*) FROM mytable >= 3
with 1 == 1
,它编译得很好,并且触发器总是执行。
您需要在整个 SELECT 语句周围添加括号SELECT COUNT (*) FROM mytable
CREATE TRIGGER mytrigger
BEFORE INSERT ON mytable
BEGIN
SELECT CASE WHEN
(SELECT COUNT (*) FROM mytable) >= 3
THEN
RAISE(FAIL, "Activated - mytrigger.")
END;
END;
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