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COMMANDS
ALTER TABLE
ALTER TABLE table_name ADD column_name datatype;
ALTER TABLE lets you add columns to a table in a database.
AND
SELECT column_name(s) FROM table_name WHERE column_1 = value_ AND column_2 = value_2;
AND is an operator that combines two conditions. Both conditions must be true for the
row to be included in the result set.
AS
SELECT column_name AS 'Alias' FROM table_name;
AS is a keyword in SQL that allows you to rename a column or table using an alias.
AVG()
SELECT AVG(column_name) FROM table_name;
AVG() is an aggregate function that returns the average value for a numeric column.
BETWEEN
SELECT column_name(s) FROM table_name WHERE column_name BETWEEN value_1 AND value_2;
The BETWEEN operator is used to filter the result set within a certain range. The values can
be numbers, text or dates.
CASE
SELECT column_name, CASE WHEN condition THEN 'Result_1' WHEN condition THEN 'Result_2' ELSE 'Result_3' END FROM table_name;
CASE statements are used to create different outputs (usually in the SELECT statement). It
is SQL's way of handling if-then logic.
COUNT()
SELECT COUNT(column_name) FROM table_name;
COUNT() is a function that takes the name of a column as an argument and counts the
number of rows where the column is not NULL.
CREATE TABLE
CREATE TABLE table_name ( column_1 datatype, column_2 datatype, column_3 datatype );
CREATE TABLE creates a new table in the database. It allows you to specify the name of
the table and the name of each column in the table.
DELETE
DELETE FROM table_name WHERE some_column = some_value;
DELETE statements are used to remove rows from a table.
GROUP BY
SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name;
WHERE column_name LIKE pattern;
LIKE is a special operator used with the WHERE clause to search for a specific pattern in a
column.
LIMIT
SELECT column_name(s) FROM table_name LIMIT number;
LIMIT is a clause that lets you specify the maximum number of rows the result set will
have.
MAX()
SELECT MAX(column_name) FROM table_name;
MAX() is a function that takes the name of a column as an argument and returns the
largest value in that column.
MIN()
SELECT MIN(column_name) FROM table_name;
MIN() is a function that takes the name of a column as an argument and returns the
smallest value in that column.
OR
SELECT column_name FROM table_name WHERE column_name = value_ OR column_name = value_2;
OR is an operator that filters the result set to only include rows where either condition is
true.
ORDER BY
SELECT column_name
FROM table_name ORDER BY column_name ASC | DESC;
ORDER BY is a clause that indicates you want to sort the result set by a particular column
either alphabetically or numerically.
OUTER JOIN
SELECT column_name(s) FROM table_ LEFT JOIN table_ ON table_1.column_name = table_2.column_name;
An outer join will combine rows from different tables even if the join condition is not
met. Every row in the left table is returned in the result set, and if the join condition is
not met, then NULL values are used to fill in the columns from the right table.
ROUND()
SELECT ROUND(column_name, integer) FROM table_name;
ROUND() is a function that takes a column name and an integer as an argument. It rounds
the values in the column to the number of decimal places specified by the integer.
SELECT
SELECT column_name FROM table_name;
SELECT statements are used to fetch data from a database. Every query will begin with
SELECT.
SELECT DISTINCT
SELECT DISTINCT column_name FROM table_name;
SELECT DISTINCT specifies that the statement is going to be a query that returns unique
values in the specified column(s).
SUM
