Question

晚上好，

说我有一张桌子，

CREATE TABLE test(
col_1 integer,
col_2 integer,
col_3 integer,
CONSTRAINT test_uk UNIQUE (col_1, col_2, col_3));

插入两行;

INSERT INTO test (col_1 ,col_2 ,col_3) VALUES (1,2,NULL),(1,2,NULL);

这不会引发错误，因为postgres将空值视为不相等。我可以在这三个列中添加哪些约束，我可以使用

进行更新

INSERT...... ON CONFLICT ... DO UPDATE...;

目前查询不会因上述情况而发生冲突，因为如上所述，空值不会被视为相等。

提前致谢。

Answer 1

不是很优雅，但你可以将NULL合并到一些＆＃34; reserved＆＃34;值，例如0或-1。随着＆＃34;保留＆＃34;我的意思是你知道它不会成为潜在列值的一部分。

switch effect {
            //NO BG ONLY EFFECTS
        case let (bg,effect) where (bg == 0 && effect == 0):
             print(" NO BG & none")
        case let (bg,effect) where (bg == 0 && effect == 1):
            print(" NO BG & robot")
        case let (bg,effect) where (bg == 0 && effect == 2):
            print(" NO BG & monkey")
        case let (bg,effect) where (bg == 0 && effect == 3):
            print(" NO BG & bee")
        case let (bg,effect) where (bg == 0 && effect == 4):
            print(" NO BG & elephant")
        case let (bg,effect) where (bg == 0 && effect == 5):
            print(" NO BG & mask")
        case let (bg,effect) where (bg == 0 && effect == 6):
            print(" NO BG & ghost")
        case let (bg,effect) where (bg == 0 && effect == 7):
            print(" NO BG & speed")

            //BG WIND & EFFECT CHANGED
        case let (bg,effect) where (bg == 1 && effect == 0):
            print("wind & none")
        case let (bg,effect) where (bg == 1 && effect == 1):
            print("wind & robot")
        case let (bg,effect) where (bg == 1 && effect == 2):
            print("wind & monkey")
        case let (bg,effect) where (bg == 1 && effect == 3):
            print("wind & bee")
        case let (bg,effect) where (bg == 1 && effect == 4):
            print("wind & elephant")
        case let (bg,effect) where (bg == 1 && effect == 5):
            print("wind & mask")
        case let (bg,effect) where (bg == 1 && effect == 6):
            print("wind & ghost")
        case let (bg,effect) where (bg == 1 && effect == 7):
            print("wind & speed")

            //BG CITY & EFFECT CHANGED
        case let (bg,effect) where (bg == 2 && effect == 0):
            print("city & none")
        case let (bg,effect) where (bg == 2 && effect == 1):
            print("city & robot")
        case let (bg,effect) where (bg == 2 && effect == 2):
            print("city & monkey")
        case let (bg,effect) where (bg == 2 && effect == 3):
            print("city & bee")
        case let (bg,effect) where (bg == 2 && effect == 4):
            print("city & elephant")
        case let (bg,effect) where (bg == 2 && effect == 5):
            print("city & mask")
        case let (bg,effect) where (bg == 2 && effect == 6):
            print("city & ghost")
        case let (bg,effect) where (bg == 2 && effect == 7):
            print("city & speed")

           // AND THE LIST CONTINUES...

使用INSERT ON CONFLICT在多个列上碰撞唯一约束，其中一个列可能为null

1 个答案: