learn sql

  • DISTINCT keyword in SQL

    DISTINCT keyword in SQL

     the distinct keyword in sql is used in conjunction with the select statement to remove all duplicate records and retrieve only records.
  • Sort results in SQL

    Sort results in SQL

     to sort data in sql, we use the order by clause.
  • The clause to combine JOIN data in SQL

    The clause to combine JOIN data in SQL

     in sql, the join clause is used to combine records from two or more tables in a database using common values ​​from each table.
  • INNER JOIN in SQL

    INNER JOIN in SQL

     inner join in sql is the most important and often used join type.
  • LEFT JOIN in SQL

    LEFT JOIN in SQL

     the left join in sql is the type of join that returns all records from the left table and matching records from the right table.
  • RIGHT JOIN in SQL

    RIGHT JOIN in SQL

     right join in sql is a type of join that returns all records from the right side table and matching records from the left side table.
  • FULL JOIN in SQL

    FULL JOIN in SQL

     full join in sql returns all records in the left table and the table must combine and fill in that null values ​​for values ​​do not match.
  • CARTESIAN JOIN in SQL

    CARTESIAN JOIN in SQL

     cartesian join in sql returns the cartesian product of record sets from two or more combined tables.
  • NULL value in SQL

    NULL value in SQL

     null in sql is the term used to represent a missing value.
  • Create a temporary name using ALIAS in SQL

    Create a temporary name using ALIAS in SQL

     sql alias is used to create a temporary name (called an alias) for a column or table.
  • Index (INDEX) in SQL

    Index (INDEX) in SQL

     sql index (index) is a special lookup table that database search engines can use to quickly increase the time and performance of data retrieval.
  • ALTER TABLE statement in SQL

    ALTER TABLE statement in SQL

     the alter table statement in sql is used to add, delete, and modify columns in an existing table.