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As a simple example, imagine that the data ' susan ' in the above statement was provided by user input. The user entered the string ' susan ' (without the apostrophes) in a web form text entry field, and the program used string concatenation statements to form the above SQL statement from the three fragments select * from person where name ...
Using a database-specific stored procedure that generates the surrogate key, performs the INSERT operation, and finally returns the generated key. For example, in Microsoft SQL Server, the key is retrieved via the SCOPE_IDENTITY() special function, while in SQLite the function is named last_insert_rowid().
In addition to an internal fact database, ChatScript supports PostgreSQL, MySQL, MSSQL and MongoDB both for access by scripts, but also as a central filesystem if desired so ChatScript can be scaled horizontally. A common use case is to use a centralized database to host the user files and multiple servers to scale the ChatScript engine.
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.
For example, WebDNA includes its own embedded database system. Either form of scripting (i.e., CGI or direct execution) can be used to build up complex multi-page sites, but direct execution usually results in less overhead because of the lower number of calls to external interpreters.
Data Control Language is one of the logical group in SQL Commands. SQL [1] is the standard language for relational database management systems. SQL statements are used to perform tasks such as insert data to a database, delete or update data in a database, or retrieve data from a database.
In SQL, the data manipulation language comprises the SQL-data change statements, [3] which modify stored data but not the schema or database objects. Manipulation of persistent database objects, e.g., tables or stored procedures, via the SQL schema statements, [3] rather than the data stored within them, is considered to be part of a separate data definition language (DDL).
CREATE creates an object (a table, for example) in the database, e.g.: CREATE TABLE example ( column1 INTEGER , column2 VARCHAR ( 50 ), column3 DATE NOT NULL , PRIMARY KEY ( column1 , column2 ) ); ALTER modifies the structure of an existing object in various ways, for example, adding a column to an existing table or a constraint, e.g.: