JSP里SQL语句如何使用"与"把两个条件输出来?Stringsql="select*fromcategorywheregrade=2and3";grade有三级,我想把2,3级的数据全部输出来,可是为什么只能输出2级的,3的出不来-----------------------------

Question

JSP 里SQL语句如何使用"与"把两个条件输出来?
String sql = "select * from category where grade = 2 and 3";
grade有三级,我想把2,3级的数据全部输出来,可是为什么只能输出2级的,3的出不来
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public List getChilds(){
Listcategories = new ArrayList();
Connection conn=DB.getConn();
Statement stmt = DB.getStatement(conn);
String sql = "select * from category where grade = 2 and 3";
ResultSet rs = DB.getResultSet(stmt,sql);
try{
while(rs.next()){
Category c = this.getCategoryFromRs(rs);
categories.add(c);
}
}catch(SQLException e){
e.printStackTrace();
}finally{
DB.close(conn);
DB.close(stmt);
DB.close(rs);
}
return categories;
}
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Answer 1

.这个SQL语句,你写错了...
select * from category where grade = 2 or grade=3
或者
select * from category where grade in ( 2,3)