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SQL
SQL Database focused on SQL CREATE DATABASE Statement and related concepts.
The CREATE DATABASE statement is used to create a new SQL database.
The DROP DATABASE statement is used to permanently delete an existing SQL database.
The BACKUP DATABASE statement is used in SQL Server to create a full backup of an existing SQL database.
The CREATE TABLE statement is used to create a new table in a database.
The DROP TABLE statement is used to permanently delete an existing table in a database.
The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.
SQL constraints are rules for data in a table.
The NOT NULL constraint enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without addin…
The UNIQUE constraint ensures that all values in a column are unique.
The PRIMARY KEY constraint uniquely identifies each record in a database table.
The FOREIGN KEY constraint establishes a link between two tables, and prevents action that will destroy the link between them.
The CHECK constraint is used to ensure that the values in a column satisfies a specific condition.
The DEFAULT constraint is used to automatically insert a default value for a column, if no value is specified.
The CREATE INDEX statement is used to create indexes on tables in databases, to speed up data retrieval.
An auto-increment field is a numeric column that automatically generates a unique number, when a new record is inserted into a table.
The most difficult part when working with dates in databases, is to be sure that the format of the date you are trying to insert/select, matches the format of the date column in the database.
An SQL view is a virtual table based on the result-set of an SQL statement. An SQL view contains rows and columns, just like a real table. The fields in the view are fields from one or more real tabl…
SQL injection is a code injection technique that can destroy your database. SQL injections are a common web hacking technique.
SQL parameters (Parameterized Queries) can be used to protect a web site from SQL injections.
SQL prepared statements can be used to protect a web site from SQL injections.
If you want your web site to store and retrieve data from a database, your web server must have access to a database-system.