Beginning SQL

The SUBSTRING() function works at the character level. The function takes three parameters: the string
out of which the substring is obtained, the first character to be obtained, and how many total characters
are required. Consider the following syntax:
SUBSTRING(string, start_character_position, length_of_string_to_obtain)
MS Access doesn’t utilize the SUBSTRING() function. Instead, it employs the MID() function, which
has exactly the same syntax and works in the same way as does the SUBSTRING() function. So if you’re
using MS Access, wherever you see SUBSTRING(), simply replace it with MID(). Oracle and IBM’s
DB2 support SUBSTRING(), but they call it SUBSTR(). If you’re using DB2 or Oracle, wherever you
see SUBSTRING(), replace it with SUBSTR().
As previously stated, the position of each character within the string is often called the character index. If
you want to extract the substring rox from the string Wrox Press, you would write the following function:
SUBSTRING(‘Wrox Press’,2,3)
Wrox Press is the string from which the substring is extracted. 2 is the character index for the first character
to be extracted, in this case the letter r. Finally, 3 is the number of characters to be extracted, in this
case rox.
The following code uses SUBSTRING() to find out the first letter of each member’s last name and the
first two letters of the name of their state of residence:
SELECT LastName, SUBSTRING(LastName,1,1), State, SUBSTRING(State,1,2)
FROM MemberDetails;
Executing the query provides the following results:
LastName SUBSTRING(LastName,1,1) State SUBSTRING(State,1,2)
Smith S Mega State Me
Gee G New State Ne
Jones J New State Ne
Jones J New State Ne
Jackson J New State Ne
Johnson J Mega State Me
Botts B Golden State Go
Simons S Mega State Me
Hills H New State Ne
Dales D Golden State Go
Doors D Mega State Me
Night N Golden State Go
Hawthorn H NULL NULL
Manipulating Data
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