In SQL statements that query data in the database, the values read can be stored in host variables.
In SQL statements that insert values into the database, update values in the database or in which calculations are performed (functions, expressions, predicates, search conditions), the values can be made available via host variables.
Other instances in which values in SQL statements can or must be provided via host variables are described in the chapter "SQL statements" as part of the description of the individual SQL statements.
A host variable is preceded in an SQL statement by a colon::host-variable
Host variables can also be vectors containing several values of the same data type. This allows you to assign aggregates to multiple columns or to transfer aggregates from multiple columns to a host variable. The syntax for vectors is language-specific and is described in the “ ESQL-COBOL for SESAM/SQL-Server” manual.