gorm joint table query - actual combat

gorm table query - actual combat

Origins

• Technology required to do a project requirement encountered by a government project
• The background of the requirement is probably as follows: there is a workers table, a worker_records table, the information of the staff is recorded in the workers table, and the staff will punch in when they go to work, and the punch record is in this worker_records table

The fields required in the workers table are as follows	The fields required in the worker_records table are as follows
gzryxm - meaning: name of staff	gzrxm——means: name of worker
gzrysjh——means: staff phone number	gzrsjh——means: mobile phone number of worker
gzrysfz——means: staff ID card	gzrsfz——means: worker ID card

• Unique ID number

• Requirements: Get the name, mobile phone number, ID number of the person who hasn't punched the card

• The drawing is as follows

gorm implementation

 db.Model(&Worker{}).Select("workers.csbh,workers.gzryxm,workers.gzrysjh,workers.gzrysfz").Joins("left join worker_records on workers.gzrysfz = worker_records.gzrsfz").Where("worker_records.gzrsfz", nil).span>Scan(&notClockedInPeopleAll)

MySQL native implementation

SELECT w.gzryxm,w.gzrysjh,w.gzrysfzFROM workers wLEFT JOIN worker_records wrON w.gzrysfz = wr.gzrsfzWHERE wr.gzrsfz IS NULL

This fulfills the requirements.

Extended

Two-table join table query can be divided into seven types, see the network diagram as follows: