备案网站公共查询,佛山app开发公司,王占山教授,淮南品牌网站建设电话一、SQL语句常用小场景
1.查询某个表信息#xff0c;表中某些字段为数据字典需要进行转义
SELECTt.ID,CASEWHEN t.DINING_TYPE 1 THEN早餐WHEN t.DINING_TYPE 2 THEN午餐WHEN t.DINING_TYPE 3 THEN晚餐END AS diningTypeStr
from student t
2.联表查询语法
select si.*…一、SQL语句常用小场景
1.查询某个表信息表中某些字段为数据字典需要进行转义
SELECTt.ID,CASEWHEN t.DINING_TYPE 1 THEN早餐WHEN t.DINING_TYPE 2 THEN午餐WHEN t.DINING_TYPE 3 THEN晚餐END AS diningTypeStr
from student t
2.联表查询语法
select si.* from student_info si
left join classed_info ci on si.classed_id ci.id
3.每个xml中可以自定义一个查询语句头 sql idqueryselect ID, ORDER_NO, WX_ORDER_NO, SCHOOL_ID, GRADE_ID, CLASSES_ID, STUDENT_ID, STUDENT_PHONE,DINING_TYPE, FOOD_TYPE, PAY_TYPE, STATUS, CREATE_ORDER_DATE_TIME, PAY_DATE_TIME,IS_DELETE, CREATOR, CREATE_TIME, MODIFIER, MODIFY_TIME from student_info/sql
4.自定义查询语句
sql idqueryif testgradeId ! null and gradeId ! and t.grade_id #{gradeId, jdbcTypeVARCHAR}/ifif testclassesId ! null and classesId ! and t.classes_id #{classesId, jdbcTypeVARCHAR}/if/sql
5.批量新增
insert idcreateList parameterTypejava.util.Listforeach collectionlist itemitem indexindex openbegin separator; close;end;INSERT INTO t_student_info (id, name)VALUES(#{item.id},#{item.name})/foreach/insert
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