NexusDB V3 Manual

Comments

Comments are text embedded in SQL statements without being executed as part of the statement.

Simple comments

NexusDB SQL supports two variations of simple comments. The first variation, which is the syntax defined by SQL:2003, starts with two minus signs (--). The second variation, which is known from traditional programming languages like C and others, starts with two slashes (//). Simple comments can only appear in single lines and are terminated by the end of the line.

The following example illustrates the use of simple comments:

// The three pound symbols define a global temporary table

CREATE TABLE ###Temp (

      c1 AUTOINC NOT NULL PRIMARY KEY, -- We don't allow null values in this column

      c2 VARCHAR(50) // This is an ordinary character string column

)

Bracketed comments

Bracketed comments start with a slash followed by an asterisk and end with an asterisk followed by a slash. Bracketed comments can be embedded anywhere in an SQL statement and may span multiple lines.

The following example illustrates the use of bracketed comments:

/*

      SQL statements must be terminated with a semicolon when they're executed as a sequence (statement block).

      We need to drop the table before recreating it.

*/

/* The IF EXISTS clause prevents an exception if the table doesn't exist */

DROP TABLE IF EXISTS /*IF EXISTS is a NexusDB extension*/ ###Temp;

CREATE TABLE ###Temp (

      c1 AUTOINC NOT NULL PRIMARY KEY,

      c2 VARCHAR(50)

);

Conformance