Joining Tables in MySQL: Tricky Scenario

Here’s a way to join tables in MySQL when linking field name is different

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MySQL Join query

The SQL query is to join Customer and Country tables.

SELECT          country_Name
FROM            customer
JOIN            country
ON customer.country = country.countryISO2;

Steps in a join query

First

Enter the name of the first table to join after the FROM keyword.

Second

Add the JOIN keyword after the table name.

Third

Enter the name of the second table to join.

Then

Add the ON keyword.

Finally

Enter the names of the two fields (the link between tables), separated by the equal (=) sign.

The table-period-field approach

The Customer table has a country field. But the Country table does not have the same field name. So in the ON condition, you give filed names following the syntax table-period-field.

Points to remember

Use the table-period-field approach when the field names are different. It is a best practice.
The order of the field names in the ON clause is irrelevant; they do not have to be in the same order as the tables in the query.

References