LEFT JOIN INNER JOIN 效率比较

显示行 0 - 29 (1,000 总计, 查询花费 0.4110 秒)
SELECT B . * , A . *
FROM content A
LEFT JOIN content_2 B ON A.id = B.id
LIMIT 0 , 1000

显示行 0 - 29 (1,000 总计, 查询花费 0.1287 秒)
SELECT B. * , A. *
FROM content A
INNER JOIN content_2 B ON A.id = B.id
LIMIT 0 , 1000

显示行 0 - 29 (10,000 总计, 查询花费 2.3492 秒)
SELECT B. * , A. *
FROM content A
LEFT JOIN content_2 B ON A.id = B.id
LIMIT 0 , 10000

显示行 0 - 29 (10,000 总计, 查询花费 0.4717 秒)
SELECT B. * , A. *
FROM content A
INNER JOIN content_2 B ON A.id = B.id
LIMIT 0 , 10000