java - 重复主键验证

Question

我正在构建一个java项目。我想检查我的表中是否已存在主键。例如我有以下代码:

private void AddProductActionPerformed(java.awt.event.ActionEvent evt) 
{                                           
    String query="INSERT INTO Products(Pro_Id ,Pro_Name,Pro_Price,Pro_Quantity,Pro_Supplier_id)VALUES ('"+Pro_Id.getText()+" ','"+Pro_Name.getText()+" ','"+Pro_Price.getText()+" ','"+Pro_Quantity.getText()+" ','"+Pro_Supplier_id.getText()+" ') ";
    executeSQLQuery(query,"Inserted");
} 

如果主键已经存在，我怎样才能收到一条消息，告诉我更改主键的条目？

Answer 1

您可以将代码放入 try catch block 中。 在 catch block 内检查 SQLException

public static final int MYSQL_DUPLICATE_PK = 1062; // Replace 1062 with exception no. you are getting in case it is different for different    database

try{
    String query="INSERT INTO Products(Pro_Id  ,Pro_Name,Pro_Price,Pro_Quantity,Pro_Supplier_id)VALUES ('"+Pro_Id.getText()+" ','"+Pro_Name.getText()+" ','"+Pro_Price.getText()+" ','"+Pro_Quantity.getText()+" ','"+Pro_Supplier_id.getText()+" ') ";
    executeSQLQuery(query,"Inserted");
} catch(SQLException e){
if(e.getErrorCode() == MYSQL_DUPLICATE_PK ){
   System.out.println("Primary key already used");
}
}