Hamid-World

In SQL, there are essentially basically two ways to INSERT data into a table: One is to insert it one row at a time, the other is to insert multiple rows at a time. Let's first look at how we may INSERT data one row at a time:

The syntax for inserting data into a table one row at a time is as follows:

INSERT INTO "table_name" ("column1", "column2", ...)
VALUES ("value1", "value2", ...)

Assuming that we have a table that has the following structure,

Table Store_Information

Column Name	Data Type
store_name	char(50)
Sales	float
Date	datetime

and now we wish to insert one additional row into the table representing the sales data for Los Angeles on January 10, 1999. On that day, this store had $900 in sales. We will hence use the following SQL script:

INSERT INTO Store_Information (store_name, Sales, Date)
VALUES ('Los Angeles', 900, 'Jan-10-1999')

The second type of INSERT INTO allows us to insert multiple rows into a table. Unlike the previous example, where we insert a single row by specifying its values for all columns, we now use a SELECT statement to specify the data that we want to insert into the table. If you are thinking whether this means that you are using information from another table, you are correct. The syntax is as follows:

INSERT INTO "table1" ("column1", "column2", ...)
SELECT "column3", "column4", ...
FROM "table2"

Note that this is the simplest form. The entire statement can easily contain WHERE, GROUP BY, and HAVING clauses, as well as table joins and aliases.

So for example, if we wish to have a table, Store_Information, that collects the sales information for year 1998, and you already know that the source data resides in the Sales_Information table, we'll type in:

INSERT INTO Store_Information (store_name, Sales, Date)
SELECT store_name, Sales, Date
FROM Sales_Information
WHERE Year(Date) = 1998

Here I have used the SQL Server syntax to extract the year information out of a date. Other relational databases will have different syntax. For example, in Oracle, you will use to_char(date,'yyyy')=1998.