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Primary key

Introduction​

Verify that the request parameters are unique. For example, the product number in the product table is unique, and the email address in the user table is unique.

Example​

Prepare data table​

Assume that there is hrm.salaries human resources system - employee salary information table, with the following structure:

--Salary table
CREATE TABLE `salaries` (
   `emp_no` int(11) NOT NULL,
   `salary` int(11) NOT NULL,
   `from_date` date NOT NULL,
   `to_date` date NOT NULL,
   PRIMARY KEY (`emp_no`,`from_date`),
   CONSTRAINT `salaries_ibfk_1` FOREIGN KEY (`emp_no`) REFERENCES `employees` (`emp_no`) ON DELETE CASCADE
)

You can see from the above table structure:

  • The primary key is the combination of "employee number" emp_no and "start date" from_date, which is used to uniquely identify a salary record. The value must be unique
  • The employee number field emp_no is used as a foreign key. For foreign key constraints, please refer to Foreign Key

Example 1: Normal request​

POST http://127.0.0.1:21000
Content-Type: application/json;charset=utf-8
{
   "jsonrpc": "2.0",
   "method": "hrm.salaries.add",
   "params": {
     "empNo": 10010,
     "salary": 10000,
     "fromDate": "2023-10-01",
     "toDate": "2023-10-31"
   },
   "id": "client-unique-request-id"
}

Response​

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
{
   "jsonrpc": "2.0",
   "result": {
     "empNo": 10010,
     "fromDate": "2023-10-01"
   },
   "id": "client-unique-request-id"
}

Example 2: Bad request​

Submit the request repeatedly, and it is detected that the combination of "employee number" and "start date" already exists, and the response is incorrect.

POST http://127.0.0.1:21000
Content-Type: application/json;charset=utf-8
{
   "jsonrpc": "2.0",
   "method": "hrm.salaries.add",
   "params": {
     "empNo": 10010,
     "salary": 10000,
     "fromDate": "2023-10-01",
     "toDate": "2023-10-31"
   },
   "id": "client-unique-request-id"
}

Response error​

HTTP/1.1 400 Bad Request
Content-Type: application/json; charset=utf-8
{
   "jsonrpc": "2.0",
   "error": {
     "code": -32600,
     "message": "checking for primary key conflicts: duplicate primary key in hrm.salaries [empNo fromDate]",
     "data": {
       "errorCode": "EU.Constraint.PK.Duplicated",
       "errorDetails": [
         {
           "constraint": "PrimaryKeyDuplicated",
           "field": [
             "empNo",
             "fromDate"
           ],
           "fieldValue": [
             10010,
             "2023-10-01"
           ],
           "location": "hrm.salaries",
           "message": "duplicate primary key in hrm.salaries.[empNo fromDate] [10010 2023-10-01]"
         }
       ],
       "errorMessage": "duplicate primary key in hrm.salaries [empNo fromDate]"
     }
   },
   "id": "client-unique-request-id"
}

Tested on Luwak 1.13.0

Last updated on