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mysql中避免重复插入相同数据(insert if not exists)

2013-05-09 17:23 225 查看
INSERT INTO admins_groups (admin_id,group_id) values (11,22) WHERE NOT EXISTS (SELECT admin_id FROM admins_groups WHERE admin_id=1 and group_id=14);

该操作 是错误的

INSERT INTO groups (admin_id,out_id) select admin_id,group_id from admins_groups WHERE NOT EXISTS (SELECT admin_id FROM admins_groups WHERE admin_id=1 and group_id=222)
LIMIT 1;

如果符合后面的条件 可以插入多条数据,但LIMIT 1 把它限制为一条

INSERT INTO groups (admin_id,out_id) select 1,group_id from admins_groups WHERE NOT EXISTS (SELECT admin_id FROM admins_groups WHERE admin_id=1 and group_id=222) LIMIT 1;

如果符合后面的条件 插入一条 admin_id = 1 的 数据.
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