第 17.1 节:在具有相同名称的列上连接三个表
sql
CREATE TABLE Table1 (
id INT UNSIGNED NOT NULL,
created_on DATE NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE Table2 (
id INT UNSIGNED NOT NULL,
personName VARCHAR(255) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE Table3 (
id INT UNSIGNED NOT NULL,
accountName VARCHAR(255) NOT NULL,
PRIMARY KEY (id)
);
创建表后,你可以执行一个 SELECT 查询来获取三个表中所有相同的 id:
sql
SELECT
t1.id AS table1Id,
t2.id AS table2Id,
t3.id AS table3Id
FROM Table1 t1
LEFT JOIN Table2 t2 ON t2.id = t1.id
LEFT JOIN Table3 t3 ON t3.id = t1.id;