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SQL programmingYou can use the HCL OneDB™ implementation of the SQL language to develop applications for HCL OneDB™ database servers.
Guide to SQL: SyntaxThe HCL OneDB™ Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the HCL OneDB™ dialect of the SQL language.
SQL statementsThis chapter describes the syntax and semantics of SQL statements that are recognized by HCL OneDB™.
CREATE TABLE statementUse the CREATE TABLE statement to create a new permanent table in the current database.
Specialized columnsYou can create specialized columns to support Enterprise Replication, high availability, or row-level auditing.
Using the WITH REPLCHECK KeywordsUse the WITH REPLCHECK keywords to create the ifx_replcheck shadow column that Enterprise Replication uses for consistency checking.

Using the WITH REPLCHECK Keywords

Use the WITH REPLCHECK keywords to create the ifx_replcheck shadow column that Enterprise Replication uses for consistency checking.

The ifx_replcheck column is a visible shadow column because it can be indexed and can be viewed in system catalog tables. After you create the ifx_replcheck shadow column, you must create a new unique index on the primary key and the ifx_replcheck column. The ifx_replcheck shadow column must be the last column in the index. Enterprise Replication uses that index to speed consistency checking.

For most database operations, the ifx_replcheck column is hidden. For example, if you include the WITH REPLCHECK keywords when you create a table, the ifx_replcheck column has the following behavior:

It is not returned by queries that specify an asterisk ( * ) as the projection list, as in the statement:
```
SELECT * FROM tablename;
```
It does appear in DB-Access when you ask for information about the columns of the table.
It is included in the number of columns (ncols) in the systables system catalog table entry for tablename.

To view the contents of the ifx_replcheck column, you must explicitly specify the columns in the projection list of a SELECT statement, as the following example shows:

SELECT ifx_replcheck FROM customer;

Example

In the following example, the ifx_replcheck shadow column is added to the customer table:

CREATE TABLE customer (id int) WITH REPLCHECK;