使用Union/Union All插入无法插入所有行

-- 错误示例
SELECT id, name FROM table1
UNION
SELECT id, age FROM table2; -- name 和 age 数据类型不匹配

-- 正确示例
SELECT id, CAST(name AS VARCHAR(50)) AS name FROM table1
UNION
SELECT id, CAST(age AS VARCHAR(50)) AS name FROM table2;

-- 错误示例
SELECT id, name FROM table1
UNION
SELECT id FROM table2; -- 列数不一致

-- 正确示例
SELECT id, name FROM table1
UNION
SELECT id, '' AS name FROM table2;

-- 错误示例
SELECT id, name FROM table1
UNION
SELECT id, NULL AS name FROM table2; -- 可能会丢失某些行

-- 正确示例
SELECT id, name FROM table1
UNION ALL
SELECT id, NULL AS name FROM table2;

-- 检查并处理约束
ALTER TABLE target_table DISABLE TRIGGER ALL; -- 禁用触发器
-- 执行插入操作
ALTER TABLE target_table ENABLE TRIGGER ALL; -- 启用触发器

-- 授予权限
GRANT INSERT ON target_table TO user_name;

-- 创建目标表
CREATE TABLE target_table (
    id INT,
    value VARCHAR(100)
);

-- 使用 UNION ALL 插入数据
INSERT INTO target_table (id, value)
SELECT id, name FROM source_table1
UNION ALL
SELECT id, description FROM source_table2;