mysql数据库如何处理包含多个值的字段

Question

i have MYSQL database where a table have a field that contains multiple values in each cell. where these values are a foreign key of another table.

inspection_date:

• siteID (primary key)
• employeeID(foreign key)
• inspectionDate

where the emplyee field will have multiple values be cause more than one employee had done the inspection.

employee

• employeeID(primary key)
• employeeName

can anyone help me to use select query

mysql :

$query_site_location =$wpdb->get_results("select DISTINCT 
                      l.siteID,
                      l.locationName, 
                      n.inspectionDate,
                      s.employeeID
                       from site_location l
                       LEFT    
                       JOIN inspection_info n
                       on l.siteID = n.siteID
                       LEFT  
                       JOIN employee s
                       on n.employeeID = s.employeeID");

the result must be in the field of employee (6-7) for the first row

Answer 1

A THIS relation is many to many we must create a third entity in order to handle the primary keys of both tables.

employee:

employeeID(PRIMARY KEY)
employeeName

inspection_info:

inspectionID(PRIMARY KEY)
inspectionDate
employeeID

inspection_site:

inspectionID(PRIMARY KEY)

siteID(PRIMARY KEY)