MySQL uses Group_concat to combine multiple data display methods

Situation Analysis:

1. Table Course

ID Name

1 Lesson One

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2. Table Course_teacher

ID course_id teacher_name

1 1 Teacher One

2 1 Teacher Two

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A statement is required to isolate the course ID, course name, teacher name

Using the Group_concat () function,

Method: Select C.*,group_concat (t.teacher_name) From course C left joins Course_teacher T on c.id=t.course_id where c.id=1

Default "," split, can also modify Group_concat (T.teacher_name SEPARATOR "-")

Note that the low version of MySQL will appear to return blobs, in order to be compatible with the old version of MySQL we need to convert the Teacher_name field

such as: Group_concat (CAST (t.teacher_name as Char) SEPARATOR "-")

MySQL uses Group_concat to combine multiple data display methods