SQL/MX Glossary

Glossary

HP NonStop SQL/MX Glossary—523732-002

Glossary-5

clustering key

clustering key. A storage key made up of a set of columns in a table whose values act as

logical row-ids. The set of columns that make up the clustering key must guarantee

uniqueness. See also primary key.

COBOL preprocessor. See SQL preprocessor.

collation. A convention that governs the ordering of any two character strings formed with

characters from their character sets. SQL/MX supports only the default collation that is

based on binary ordering. See also character set.

column. A vertical component of a table; the relational representation of a field in a record.

A column contains one data value for each row of the table. Contrast with row.

column attribute. An attribute that describes the data that a column can contain and how

the data is stored. Column attributes include data type, default value, heading, row

order (ascending or descending), nullable, and UPSHIFT.

column default value. The value inserted in a row when an INSERT statement omits a

value for a column.

column heading. Text specified in a HEADING clause in a CREATE TABLE or ALTER

TABLE statement to replace the column name in an MXCI display.

column name. An SQL identifier used to identify a column in a table. A table name or

correlation name can qualify the column name to make it unique within an SQL

statement.

command file. See OBEY command file.

command-line interface (CLI). An interface between a software subsystem and a user in

which the user enters computer-language commands at a prompt. MXCI and SQLCI

are examples of command-line interfaces.

committed transaction. A transaction that successfully completed its changes to the

database.

comparable data types. Data types such that a value of one data type can be compared to

a value of the other data type. See also compatible data types.

comparison predicate. A predicate that compares the values of sequences of expressions,

or the values of sequences of row values that are the result of row subqueries.

compatible data types. Data types such that a value of one data type can be assigned to a

column or parameter of the other data type, and columns of the two data types can be

combined using arithmetic operations. Compatible data types are also comparable.