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The type_info data type means that its value is a reference to an ASN.1 type. The ref_to_table data type means that its value is a reference to another instance of SQL table (ERROR table in this case). While we know that in real SQL we can't have multiple instances of the same table, let's imagine for the purposes of accuracy of our description ...
For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, [ 4 ] for example: (1234, 'Big Company Inc.', '123 East Example Street', '456 West Example ...
column position (one based) Possible fields: Y row row position (one based). If omitted, most recently encountered value is used. E expression expression for the cell K value value of the cell C column column reference R row row reference G defines shared value D defines shared expression S references shared value or shared expression N
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
[5] Codd defines an atomic value as one that "cannot be decomposed into smaller pieces by the DBMS (excluding certain special functions)" [6] meaning a column should not be divided into parts with more than one kind of data in it such that what one part means to the DBMS depends on another part of the same column.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
An example of a database that has not enforced referential integrity. In this example, there is a foreign key (artist_id) value in the album table that references a non-existent artist — in other words there is a foreign key value with no corresponding primary key value in the referenced table.
A table can be useful even if none of the cells have content. For example, the background colors of cells can be changed with cell parameters, making the table into a diagram, like meta:Template talk:Square 8x8 pentomino example. An "image" in the form of a table is much more convenient to edit than an uploaded image.