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Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL . [ 1 ] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.
PreparedStatement allows the dynamic query to vary depending on the query parameter. [11] CallableStatement – CallableStatement is a subinterface of the Statement interface. [11] It is used for executing stored procedures on the database. [11] [12] Both input and output parameters must be passed into the database for stored procedures. [13]
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.
They may be included in any order (see Examples below). Certain templates have the parameter "on" by default; see the main table for all alternate options. If a row renders identically to a previous row, it means the current template does not support that option and {{ tlg }} needs to be used instead.
This template uses Module:Check for unknown parameters. All allowed parameters must be listed at {{#invoke:Check for unknown parameters|...}} in the template's own code. A call with an unlisted parameter may cause a warning in previews and may add a tracking category. There are two optional parameters preview and category.
} extracts a specified template's parameters and performs a variety of tasks to aid in its documentation or WP:TFD merge nominations. It itself takes two parameters: |1=, the output format; and |base=, the title of a template. The compare function requires a third parameter, |other=. {} must always be substituted. Its usage is demonstrated below.
All parameters are separated with the pipe character "|". The first "parameter" is always the name of the template that you wish to use and as such is not formally a parameter at all. In this case, it is Querylink. The first formal parameter passed to the template should be the name of the internal page that you wish to link.
The "example" entry allows you to display an example of an entry that a person might make for this variable, written exactly as a person might type it, character-for-character; if the type of entry has already been set with the "type" parameter (see below), then the example should reflect this (i.e., if the type has been set to "wiki-page-name ...