Preprocessor2 treats SQL character strings as a third kind of host variable that is neither input nor output.
An SQL string is a series of characters used to complete an embedded SQL statement. It is not an input or an output variable because it does not correspond to a field in a row of a table.
Character Strings as Host Variables
SQL character strings are a distinct category of host variable because some host languages apply special rules to them. Those rules are detailed in the language-dependent sections of Teradata® Preprocessor2 for Embedded SQL Programmer Guide, B035-2446.
Character strings can require a leading COLON character when referenced in an embedded SQL statement. For details, see the individual statement syntax documentation in Teradata Vantage™ - SQL Data Manipulation Language, B035-1146 and in this section.
Statements That Use Strings as Host Variables
The following table lists embedded SQL statements that use SQL strings as host variables.
| This SQL statement … | Uses an SQL string as a host variable … |
|---|---|
| CHECKPOINT | when the checkpoint label is expressed as a host variable. |
| DATABASE | when the database name is expressed as a host variable. |
| EXECUTE IMMEDIATE | when the SQL statement string is expressed as a host variable. |
| LOGON | for the logon string. |
| PREPARE | when the SQL statement string is expressed as a host variable. |
| SET CHARSET | when the character set name is expressed as a host variable. |