-- generated always as的使用 CREATE TABLE t1( c1 INT, c2 DOUBLE(20,19) , c3 INT GENERATED ALWAYS AS(c1*2)); SELECT *FROM t1; INSERT INTO t1(c1,c2) VALUE(2,RAND()*10); DROP TABLE t1; concat在mysql中是连接 SELECT CONCAT('a','6','cc'); SELECT IF('男'='男','先生','女