EXPERT RESPONSE
The standard SQL substring function is
SUBSTRING(string FROM start FOR length)
Microsoft SQL/Server, Sybase, MySQL and PostgreSQL all support this syntax.
Other databases may also support it
(I have not done an exhaustive survey). Double-check
by looking it up in your database documentation.
In Microsoft SQL/Server, Sybase, and MySQL, you can also use
SUBSTRING(string, start, length)
In Microsoft Access and MySQL, you can use
MID(string, start, length)
In Oracle, use
SUBSTR(string, start, length)
A good reference for SQL functions is
Chapter 4, SQL Functions, the sample chapter
of O'Reilly's book SQL in a Nutshell
by Kevin Kline and Daniel Kline (ISBN 1-56592-744-3).
For your specific requirement, you would write
SUBSTRING(string FROM 1 FOR 8)
Depending on your database, you might also be able to write
LEFT(string, 8)
because the LEFT function, in those databases that support it,
starts at position 1. For More Information
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