如何在SQL中组合值

SELECT FirstName + ' ' + LastName AS FullName FROM Users;

SELECT CONCAT(FirstName, ' ', LastName) AS FullName FROM Users;

SELECT FirstName || ' ' || LastName AS FullName FROM Users;

SELECT FirstName || ' ' || LastName AS FullName FROM Users;

-- SQL Server
SELECT ISNULL(FirstName, '') + ' ' + ISNULL(LastName, '') AS FullName FROM Users;

-- MySQL
SELECT CONCAT(COALESCE(FirstName, ''), ' ', COALESCE(LastName, '')) AS FullName FROM Users;

-- PostgreSQL
SELECT COALESCE(FirstName, '') || ' ' || COALESCE(LastName, '') AS FullName FROM Users;

-- Oracle
SELECT COALESCE(FirstName, '') || ' ' || COALESCE(LastName, '') AS FullName FROM Users;