Mysql学习mysql中替代null的IFNULL()与COALESCE()函数详解

MYSQL教程
SELECT ISNULL(business_name,'no business_name') AS bus_isnull FROM business WHERE id=2

MYSQL教程
Incorrect parameter count in the call to native function 'isnull'

MYSQL教程
SELECT IFNULL(business_name,'no business_name') AS bus_ifnull FROM business WHERE id=2

MYSQL教程
SELECT IFNULL(business_name,'no business_name') AS bus_ifnull FROM business WHERE id=1

MYSQL教程
SELECT COALESCE(business_name,'no business_name') AS bus_coalesce FROM business WHERE id=2

MYSQL教程
SELECT COALESCE(business_name,'no business_name') AS bus_coalesce FROM business WHERE id=1

MYSQL教程
SELECT COALESCE(business_name,district_id,id) AS bus_coalesce FROM business WHERE id=2

MYSQL教程
SELECT * FROM business WHERE ISNULL(business_name)

MYSQL教程
SELECT * FROM business WHERE business_name IS NULL

MYSQL教程
SELECT * FROM business WHERE business_name IS NOT NULL