Sep 16, 2019 4:57:56 PM 共348人围观 0人评论

# 四舍五入 SELECT ROUND-1.45; SELECT ROUND45.55; SELECT ROUND45.554588,2; # 向上取整 SELECT CEIL1.002; # 向下取整 SELECT FLOOR4.99; # 截断 SELECT TRUNCATE4.99151,1; # 取余 * mo......

Sep 16, 2019 2:56:04 PM 共330人围观 0人评论

SELECT SUBSTR'李莫愁爱上了陆展元',7 out_put; # 从第7个字符开始截取SELECT SUBSTR'李莫愁爱上了陆展元',1,3 out_put;# 从第1个字符开始截取3个SELECT CONCATUPPERSUBSTRemployees.last_name,1,1,LOWERSUBSTRe......

Sep 16, 2019 2:28:56 PM 共306人围观 0人评论

# UTF-8字符集下SELECT LENGTH"john"; # 1个字母占1个字节SELECT LENGTH"张三丰hahaha"; # 1个汉字占3个字节# GBK字符集下 SELECT LENGTH"john"; # 1个字母占1个字节 SELECT LENGTH"张三丰hahaha"; # 1个汉字占......

Sep 16, 2019 2:12:57 PM 共312人围观 0人评论

# 案例一 SELECT *,employees.salary*12*1+IFNULLemployees.commission_pct,0 年薪 FROM employees ORDER BY employees.salary*12*1+IFNULLemployees.commission_pct,0 DESC; ......

Sep 16, 2019 1:51:47 PM 共350人围观 0人评论

# 案例一SELECT employees.last_name,employees.commission_pctFROMemployeesWHEREcommission_pct = null;# 案例二SELECT employees.last_name,employees.salaryFROMemployeesWHE......