我有以下 SQL 语句(用于 SQL Server):
INSERT INTO t1 (c1, c2)
VALUES (1, CASE WHEN (SELECT MAX(c2) FROM t1 AS maxV) IS NOT NULL THEN maxV+1 ELSE 1 END);
我收到一个错误:“列名 'maxV' 无效”
为什么?
我有以下 SQL 语句(用于 SQL Server):
INSERT INTO t1 (c1, c2)
VALUES (1, CASE WHEN (SELECT MAX(c2) FROM t1 AS maxV) IS NOT NULL THEN maxV+1 ELSE 1 END);
我收到一个错误:“列名 'maxV' 无效”
为什么?
尝试使用COALESCE
:
INSERT INTO t1 (c1, c2)
SELECT 1, COALESCE(MAX(c2), 0) + 1
FROM t1
试试这个...
INSERT INTO t1 (c1, c2)
VALUES (
1,
CASE
WHEN (SELECT MAX(c2) FROM t1) IS NOT NULL
THEN (SELECT MAX(c2)+1 FROM t1)
ELSE 1
END);
另一种方法...
INSERT INTO t1 (c1, c2)
VALUES (1, ISNULL(SELECT MAX(c2) FROM t1, 0)+1);