SQL Articles

• Normalization of a database

  Database theory: let's see how to normalize a database in the first, second and third normal form.

• Using UNION to combine the results from two tables

  Let's see how to merge the results from two tables using the UNION operator homogeneous

• The opposite of an INNER JOIN or to obtain the records do not match

  Let's see how to get the opposite result of an INNER JOIN retrieves only those records that are not reflected in table JOIN

• UPDATE of two or more tables

  Example of relationships in writing, in this case, editing, updating via SQL, the UPDATE statement, data related to each other.

• Manage JOIN three tables

  Sophisticated example of a query between tables in the report, with SQL JOIN statement.

• Assign names to the fields in a table using the prefixes

  A simple but useful advice about naming fields to a table, using a prefix makes sense, different from table to table.

• Delete records from multiple related tables

  Example of relationships in writing, in this case, delete, delete via SQL, with the DELETE statement, data related to each other.

• Count the number of characters used in a field

  The LEN function allows SQL to count the length of the field in a record extracted through a query.

• Assign and revoke permissions with GRANT and REVOKE

  SQL GRANT and REVOKE statements to assign and revoke permissions to users in a database.

• Create indexes on a table via SQL

  How to create indexes on a table via SQL using the CREATE INDEX command.

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