数据表是这样的 select * from water_level_records m where ( select count(*) from water_level_records n where m.device_id = n.device_id and m.record_time < n.record_time ) 这个sql的逻辑是把一个表当做两个表关联来使用,当满足m的记录时间小于n的记录时间的数量<1 即只有一个相等时返回,即是时间的最大值, 如果为<2 则是为前两大的值,
SQL取出 所有周六 周日的日期 create table SatSun([id] int identity(1,1),[date] datetime,[weekday] char(6)) go declare @datetime datetime,@weekday char(6) set @datetime='2007-1-1' while @datetime<='2007-12-31' begin select @weekday=datename(weekday,@datetime) if
resultset 对象获取行字段数据时报:java.sql.SQLException: Column 'id' not found. 代码: String sql="SELECT d.content,c.name AS categoryName FROM news_detail d,news_category c WHERE d.categoryId=c.id"; Object[] params ={}; System.out.println(this.executeQuery(sq
1. 原生sql: select a.id,a.name from a SQLQuery sqlQuery=this.getSession().createSQLQuery(sb.toString()); List list = sqlQuery.list(); 在action处理成map: 2.hql: select new map(a.id as id,a.name as name) from a this.getHibernateTemplate().find(sb.toString())
如 有个表里有字段 id,name,..... 当name是重复时取其id最大的一条记录 select max(id) id,name from 表 group by name --最小用mini --如果表中还有其他字段要查出,那么select * from 表 where id in(select max(id) from 表 group by name )
在注册新用户的时候报错: (sqlite3.OperationalError) no such table: users [SQL: 'SELECT users.id AS users_id, users.email AS users_email, users.username AS users_username, users.role_id AS users_role_id, users.password_hash AS users_password_hash, users.confirmed
1.错误描述 org.hibernate.exception.GenericJDBCException: error executing work at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(Sql
1:id 列要设置成自增,自动赋值 java.sql.SQLException: Field 'id' doesn't have a default value at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3593) at com.mysql.jdbc.MysqlIO.checkErrorPacke