SQL Flashcards
SQL
Structured Query Language
RDBMS
Relational Database Management System
Lets you add columns to a table in a database
ALTER TABLE
ALTER TABLE table_name
ADD column datatype;
Is an operator that combines two conditions. Both conditions must be true for the row to be included in the result set
AND
SELECT column_name(s)
FROM table_name
WHERE column_1 = value_1 AND column_2 = value_2;
Is a keyword in SQL that allows you to rename a column or table using an alias
AS
SELECT column_name AS ‘Alias’
FROM table_name;
Is an aggregate function that returns the average value for a numeric column.
AVG
SELECT AVG(column\_name) FROM table\_name;
The _____ operator is used to filter the result set within a certain range. The values can be numbers, text or dates.
BETWEEN
SELECT column_name(s)
FROM table_name
WHERE column_name BETWEEN value_1 AND value_2;
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.
COUNT
SELECT COUNT(column\_name) FROM table\_name;
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.
CREATE TABLE
CREATE TABLE table_name (
column_1 datatype,
column_2 datatype,
column_3 datatype
);
Is used to remove rows from a table.
DELETE
DELETE FROM table_name
WHERE some_column = some_value;
Is a clause in SQL that is only used with aggregate functions. It is used in collaboration with the SELECT statement to arrange identical data into groups.
GROUP BY
SELECT COUNT(*)
FROM table_name
GROUP BY column_name;
Will combine rows from different tables if the join condition is true.
INNER JOIN
SELECT column_name(s)
FROM table_1
JOIN table_2
ON table_1.column_name = table_2.column_name;
Is used to add a new row to a table.
INSERT
INSERT INTO table_name (column_1, column_2, column_3)
VALUES (value_1, ‘value_2’, value_3);
Is a special operator used with the WHERE clause to search for a specific pattern in a column.
LIKE
SELECT column_name(s)
FROM table_name
WHERE column_name LIKE pattern;
Is a clause that lets you specify the maximum number of rows the result set will have.
LIMIT
SELECT column_name(s)
FROM table_name
LIMIT number;
Is a function that takes the name of a column as an argument and returns the largest value in that column.
MAX
SELECT MAX(column\_name) FROM table\_name;
Is a function that takes the name of a column as an argument and returns the smallest value in that column.
MIN
SELECT MIN(column\_name) FROM table\_name;
Is an operator that filters the result set to only include rows where either condition is true.
OR
SELECT column_name
FROM table_name
WHERE column_name = value_1
OR column_name = value_2;
Is a clause that indicates you want to sort the result set by a particular column either alphabetically or numerically.
ORDER BY
SELECT column_name
FROM table_name
ORDER BY column_name ASC|DESC;
Will combine rows from different tables even if the 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.
OUTER JOIN
SELECT column_name(s) FROM table_1
LEFT JOIN table_2
ON table_1.column_name = table_2.column_name;
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.
ROUND
SELECT ROUND(column\_name, integer) FROM table\_name;
Specifies that the statement is going to be a query that returns unique values in the specified column(s).
SELECT DISTINCT
SELECT DISTINCT column_name FROM table_name;
Is a function that takes the name of a column as an argument and returns the sum of all the values in that column.
SUM
SELECT SUM(column\_name) FROM table\_name;
Allows you to edit rows in a table.
UPDATE
UPDATE table_name
SET some_column = some_value
WHERE some_column = some_value;
