Basic SQL Commands – SQL For Programmers

Before we get into the specifics of the commands that can be used within a stored procedure, I think it would be helpful to review some of the more basic commands that we can use that don’t really need a whole lot of discussion.

I know I said I wasn’t going to spend a lot of time on the basics, but my research indicates that a lot of people are searching for basic sql commands and very few sites are addressing that issue specifically.

So, if this is unhelpful to you, just consider this Dave’s SEO experiment.

Basic SQL Commands

Command Description
SELECT The SELECT statement returns a set of records from a table or view.  It can be used in combination with JOIN to return a set of records that are a mashup of records from multiple tables but the end result from a programming perspective is that it looks like it came from one table.  The set of records returned can be narrowed by using the WHERE clause and the order that they are returned can be set by using the ORDER BY clause.

Most common form:
SELECT field1, field2, etc FROM tableName WHERE conditions ORDER BY listOfFields

INSERT INSERT adds new records to the table.  This can be used in combination with a sub-SELECT to insert records from another table into the current table.

Most common form:
INSERT INTO tableName(field1,field2) VALUES(value1,value2)

UPDATE This is most often used in combination with the WHERE clause to update a record in a table.

Most common form:
UPDATE tableName SET field1=value1, field2=value2 WHERE condition

DELETE When you need to delete a record in your table, or a set of records, you will use the DELETE statement.

Most common form:
DELETE FROM tableName WHERE condition

WHERE The WHERE clause specifies what set of records the operation should be performed on.  We have discussed various operators in previous posts.  The most common are: =, <>, <, >, IN, and LIKE
IN IN is used with the WHERE clause to determine if the field is equal to any of the items in a list.
LIKE We discussed this one a few posts ago.  Most are familiar with the common form, LIKE ‘%content%’ to determine if ‘content’ is in the field.  But there are other useful forms of this operator as well.  Check out the list of previous posts below.
ORDER BY Most often used with the SELECT statement (and I really can’t think of any other place it is used), this controls the order the records are returned.  Most often this is a list of fields.  By default it lists everything in ascending order.  If you want the items in descending order, use the DESC modifier.

My favorite resource for SQL syntax reference is http://www.w3schools.com/sql/.

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