In SQL, if you want to remove a table from a database, you need to use the DROP TABLE statement.
That destroys the table and all its data.
Continue readingHow to Drop a Foreign Key in SQLite
Normally if you need to drop a foreign key in SQL, you’d use the ALTER TABLE statement. But if you’re using SQLite, that’s not an option.
SQLite DROP TABLE
In SQLite, you can drop a table with the DROP TABLE statement.
You can optionally add the IF EXISTS clause to suppress any errors that might occur if the table doesn’t exist.
Also, if the table is referenced by a foreign key, there are a few things to be aware of.
Continue readingSQL DROP COLUMN for Beginners
In SQL, if you want to remove a column from a table, you need to use the ALTER TABLE statement with the DROP COLUMN clause.
That removes the column and all its data.
Continue readingSQL Tutorial for Beginners
In this SQL tutorial for beginners, you will create your own database, insert data into that database, and then run queries against that database.
This SQL tutorial will get you running SQL queries in no time!
Continue readingHow to Rename a Column in SQL
This article provides a quick example of renaming a table in SQL.
Most of the major RDBMSs allow you to rename a column with the ALTER TABLE statement. SQL Server is an exception.
SQL ALTER TABLE for Beginners
In SQL, the ALTER TABLE statement modifies the definition of an existing table.
You can use ALTER TABLE to alter, add, or drop columns and constraints.
Depending on your DBMS, the ALTER TABLE statement can also be used to reassign and rebuild partitions, or disable and enable constraints and triggers.
SQL UNION Clause for Beginners
In SQL, the UNION clause concatenates the results of two queries into a single result set.
You can use the UNION clause with or without the ALL argument:
UNION ALL– Includes duplicates.UNION– Excludes duplicates.
Some RDBMSs also accept UNION DISTINCT, which is the equivalent to UNION. That is, it excludes duplicates.
Below are some basic examples to demonstrate how it works.
Continue readingSQL AVG() for Beginners
In SQL, the AVG() function is an aggregate function that returns the average of all values in a given expression.
It can also be used to return the average of all distinct (unique) values in an expression.
The expression must be numeric (it cannot be character string, bit string, or datetime).
Below are some basic examples to demonstrate how it works.
Continue readingSQL SUM() for Beginners
In SQL, the SUM() function is an aggregate function that returns the sum of all values in a given expression.
It can also be used to return the sum of all distinct (unique) values in an expression.
The expression must be numeric (it cannot be character string, bit string, or datetime).
Below are some basic examples to demonstrate how it works.
Continue reading