3.7 Relational databases and structured query language (SQL)

• In SQL, we can create a database using the CREATE DATABASE statement
• The foreign key links one or more tables together by referencing the primary key from another table
• A primary key is an attribute that uniquely identifies every record within the table
• To delete an entire table from a database, use the DROP TABLE statement.
• A join is used to combine data from two or more tables into a single result set
• The SELECT statement is used to retrieve data from one or more tables.
• A WHERE clause is used with the SELECT statement to filter rows based on specific conditions.
• An inner join returns only rows that have matching values in both tables
• To delete all records with a specific value in a column, use DELETE FROM tablename WHERE condition
• To add data to a table, use the INSERT INTO statement.
• An index is used to speed up searching through large amounts of data
• A left outer join returns all rows from the first table and matching rows from the second table
• To update existing records in a table, use the UPDATE statement.
• An index is a structure that allows faster access to specific records in a table
• To remove specific rows from a table, use the DELETE FROM statement.
• The SELECT statement retrieves information from a specified table(s)
• To update multiple rows at once, use UPDATE tablename SET field1 = newvalue1 [field2 = newvalue2 ...] WHERE condition
• An index is created on columns with high selectivity to speed up queries
• An ORDER BY clause can be added to sort the results returned by the SELECT statement.
• The WHERE clause filters rows based on conditions specified
• The WHERE clause filters rows based on conditions specified
• The WHERE clause filters rows based on conditions specified
• The GROUP BY clause groups records according to specific criteria
• The WHERE clause specifies conditions that must be met for rows to be included in the output
• The WHERE clause specifies conditions that must be met for rows to be included in the output
• The GROUP BY clause groups records based on common values in one or more columns.
• The GROUP BY clause groups records based on common values in one or more columns.
• A left outer join returns all rows from the first table and matches them with any corresponding rows from the second table
• To update multiple columns at once, separate them by commas within the SET keyword
• To update multiple columns at once, separate them by commas within the SET keyword
• To create a database, use CREATE DATABASE command.
• To create a database, use CREATE DATABASE command.
• A full outer join returns all rows from both tables and matches them with any corresponding rows
• To update multiple columns at once, separate them by commas within the SET keyword
• To create a database, use CREATE DATABASE command.
• A full outer join returns all rows from both tables and matches them with any corresponding rows
• A full outer join returns all rows from both tables and matches them with any corresponding rows
• Foreign keys link related information between different tables
• Foreign keys link related information between different tables
• The GROUP BY clause groups rows by one or more columns