java - MySQL语法错误异常

Question

我无法在此处执行查询。它显示上述错误。我尝试使用“Select * from customer”查询并且它正在运行。我不知道我哪里出错了。请帮助并提前致谢。

完整的查询是 - SELECT CUSTOMER_ID,FIRST_NAME,LAST_NAME,COUNTRY,AGE,GENDER,EMAIL_ADDRESS FROM CUSTOMER WHERE FIRST_NAME='SHIVAM';

错误信息是- com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErr orException: Unknown coloumn 'SHIVAM' in 'where clause'

DefaultTableModel model;
model=(DefaultTableModel)tblSearchCustomer.getModel();
try{
 Class.forName("java.sql.Driver");
 Connection con= DriverManager.getConnection("jdbc:mysql://localhost:3306/divign","root","password");
 Statement stmt=con.createStatement();

 String sfld=(String) searchfldCB.getSelectedItem();
//this stands for Search Field(ComboBox)
 String op=(String) opCB.getSelectedItem();
//this stands for operator(ComboBox) 
 String crit=criteriaTF.getText();
 //this stands for criteria
 String query="SELECT CUSTOMER_ID,FIRST_NAME,LAST_NAME,COUNTRY,AGE,GENDER,EMAIL_ADDRESS FROM CUSTOMER WHERE" + sfld+""+op+""+crit+" ;";
 //This Query is not Executing
 ResultSet rs=stmt.executeQuery(query);
 while(rs.next()) {
     model.addRow (new Object[ ] {

       rs.getInt(1),rs.getString(2),rs.getString(3),rs.getString(4),rs.getInt(5),
       rs.getString(6),rs.getInt(7)
     } );

 }
rs.close();
stmt.close();
con.close();
 }
catch(Exception e){   
JOptionPane.showMessageDialog(null,e.toString());
}

Answer 1

当您生成查询时，where 语句中没有单引号，这意味着您将得到 WHERE FIRST_NAME=SHIVAM，因此它会尝试将 first_name 与名为 SHIVAM 的列进行比较'存在