This document provides an overview of basic SQL commands like SELECT, FROM, WHERE, ORDER BY, GROUP BY, and HAVING. It explains that data is stored in tables within a database, with each table consisting of columns and rows. The SELECT statement is used to retrieve data from these tables, and additional clauses like WHERE filter the results, while ORDER BY sorts them and GROUP BY aggregates data.

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SQL Tutorial
Basic SQL Commands

2. Agenda
• Database Basics
• SQL Commands
– SELECT … FROM
– WHERE
– ORDER BY
– GROUP BY
– HAVING
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3. Database Basics
Database
Tables
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In a relational database, data is stored in tables.

4. Database Basics
Database
Tables
Columns
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Each table consists of columns and rows. Each column is a
field in a record, and there is a column name associated with
each column.

5. Database Basics
Database
Tables
Columns
Rows
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Each row represents one record. When we say how many
records we have, we are referring to the number of rows.

6. SELECT … FROM
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SELECT “COLUMN_NAME”
FROM “TABLE_NAME”
SQL is structured similar to the English language. The basic
command for retrieving data from a database table is to
SELECT data FROM a table. Not surprisingly, the keywords
"SELECT" and "FROM" make up the core of a SQL
statement.
The syntax for “SELECT… FROM” is:

7. SELECT … FROM
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Select more than 1 column:
SELECT “COLUMN_NAME_1”, “COLUMN_NAME_2”
FROM “TABLE_NAME”
Select all columns:
SELECT *
FROM “TABLE_NAME”
Different ways of selecting data:
Select unique values:
SELECT DISTINCT “Column_Name”
FROM “TABLE_NAME”

8. WHERE
SELECT “COLUMN_NAME”
FROM “TABLE_NAME”
WHERE “CONDITION”
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Sometimes we want to retrieve only a subset of the data. In
those cases, we use the “WHERE” keyword.
The syntax for “WHERE” is:
CONDITION represents how we want the data to be filtered.

9. ORDER BY
SELECT “COLUMN_NAME”
FROM “TABLE_NAME”
WHERE “CONDITION”
ORDER BY “COLUMN_NAME” [ASC | DESC]
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When we want to list the results in a particular order
(ascending or descending), we use the ORDER BY keyword at
the end of the SQL statement.
The syntax for “ORDER BY” is:

10. MATHEMATICAL FUNCTIONS
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SQL has built-in mathematical functions to allow us to
perform mathematical operations on the data. Common
mathematical functions include:
• SUM
• AVG
• COUNT
• MAX
• MIN

11. GROUP BY
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Date Store Sales_Amount
SELECT MAX(Sales_Amount)
FROM SALES_HISTORY;
To find the highest Sales_Amount across all stores, we use the
MAX( ) function in the following SQL:
SALES_HISTORY

12. GROUP BY
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Date Store Sales_Amount
SELECT Store, MAX(Sales_Amount)
FROM SALES_HISTORY;
To find the highest Sales_Amount for each store, we change
the SELECT portion to include “Store”:
SALES_HISTORY

13. GROUP BY
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Date Store Sales_Amount
SELECT Store, MAX(Sales_Amount)
FROM SALES_HISTORY
GROUP BY Store;
However, this SELECT statement by itself is not enough. To
allow SQL to correctly calculate what we want, we need to use
the GROUP BY keyword. In the following example, the Store
column after GROUP BY tells SQL to apply the MAX
function for each Store.
SALES_HISTORY

14. SELECT “COLUMN_NAME_1”,
FUNCTION(“COLUMN_NAME_2”)
FROM “TABLE_NAME”
WHERE “CONDITION”
GROUP BY “COLUMN_NAME_1”
GROUP BY
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To summarize, the syntax for GROUP BY is as follows:

15. HAVING
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Previously we had talked about using the WHERE keyword to
filter results.
We cannot use WHERE to filter based on the result of a
function, because we need to specify the filtering condition
after SQL has calculated the function, and consequently any
filtering condition based on the function needs to be specified
after the GROUP BY phrase. So we cannot use the WHERE
keyword because it is always used before GROUP BY.
HAVING is used to filter based on the result of a function.

16. HAVING
SELECT “COLUMN_NAME_1”,
FUNCTION(“COLUMN_NAME_2”)
FROM “TABLE_NAME”
GROUP BY “COLUMN_NAME_1”
HAVING (CONDITION based on
FUNCTION)
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The syntax for HAVING is as follows:

17. HAVING
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Date Store Sales_Amount SELECT Store, SUM(Sales_Amount)
FROM SALES_HISTORY
GROUP BY Store
HAVING SUM(Sales_Amount) > 100;
Using the SALES_HISTORY table we had earlier. If we want
to sum the sales amount for each store, but only want to see
results for stores with total sales amount greater than 100, we
use the following SQL:
SALES_HISTORY

18. Order of SQL Commands
A SELECT statement has the following order:
• SELECT … FROM
• WHERE
• GROUP BY
• HAVING
• ORDER BY
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19. 1Keydata SQL Tutorial
http://www.1keydata.com/sql/sql.html
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