Fastest way to revise for the a business analyst interview. A compact yet comprehensive guide to SQL commands, Joins, examples, syntax, data types and lot more...

1. SQL
Structured Query Language
Quick Reference Cards
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SQL Command Types
Data Definition Language (DDL)
CREATE, ALTER, DROP, etc. DB objects / attributes
Data Manipulation Language (DML)
SELECT, INSERT, UPDATE, DELETE , etc data in DB
Data Control Language (DCL)
GRANT, REVOKE , etc for right & permissions
Transaction Control Language (TCL)
COMMIT, ROLLBACK, SAVEPOINT, etc for managing
transactions
Create a database
CREATE DATABASE database_name
Delete a database
DROP DATABASE database_name
Create a view in a database
CREATE VIEW view_name AS
SELECT column_name(s) FROM table_name
WHERE condition
Alter a view in a database
CREATE OR REPLACE VIEW view_name AS SELECT
columns FROM table WHERE conditions;
Delete a view in a database
DROP VIEW view_name;
Create a table in a database
CREATE TABLE "table_name"
("column_1" "data_type_for_column_1",
"column_2" "data_type_for_column_2“, ... )
Add columns in an existing table
ALTER TABLE table_name ADD column_name
datatype
Delete columns in an existing table
ALTER TABLE table_name DROP column_name
Delete a table
DROP TABLE table_name
Create a simple index
CREATE INDEX index_name
ON table_name (column_1, column_2, ...);
Create a unique index
CREATE UNIQUE INDEX index_name
ON table_name (column_1, column_2, ...);
Delete a index
DROP INDEX table_name.index_name;
Arithmetic Operators
+ (Addition), - (Subtraction), * (Multiplication),
/ (Division), % (Modulus)
Comparison Operators
= (Equal), <> (Not equal), > (Greater than),
< (Less than), >= (Greater than or equal),
<= (Less than or equal)
Logical Operators
IN ( ) - Matches a value in a list,
NOT - Negates a condition,
BETWEEN - Within a range (inclusive)
IS NULL - NULL value, IS NOT NULL - Non-NULL value
LIKE - Pattern matching with % and _
EXISTS - Condition is met if subquery returns at least
one row
Character Datatypes :CHAR(size) ,
VARCHARr2(size)…
Numeric Datatypes: NUMBER(size), NUMBER(P,S)
Date/Time Datatypes: DATE, TIMESTAMP…
Create / Alter / Delete Table
Create/Alter/Delete Views
Create / Delete Index
JOINS
Operators
Populate values for all the columns
INSERT INTO table_name VALUES (value1, value2,..);
Populate selective columns
INSERT INTO table_name (column1, column2,...)
VALUES (value1, value2,....);
Populate a table using another table
INSERT INTO table_name (column1, column2, ... )
SELECT col1, col2, ...colN
FROM second_table_name WHERE condition;
Update one or several columns in rows
UPDATE table_name
SET column_name_1 = new_value_1,
column_name_2 = new_value_2
WHERE column_name = some_value;
Updating table with data from another table
UPDATE table1
SET column1 = (SELECT expression1
FROM table2 WHERE conditions)
[WHERE conditions];
AVG Function
SELECT AVG(column or aggregate_expression)
FROM tables [WHERE conditions];
COUNT Function
SELECT COUNT(aggregate_expression)
FROM tables [WHERE conditions]
[ORDER BY expression [ ASC | DESC ]];
MAX Function
SELECT MAX(aggregate_expression)
FROM tables [WHERE conditions];
MIN Function
SELECT MIN(aggregate_expression)
FROM tables [WHERE conditions];
SUM Function
SELECT col1, col2, ... colN, SUM(aggregate_exp)
FROM tables [WHERE conditions]
GROUP BY exp1, exp2, ... expN;
Select all data from a table
SELECT * FROM table_name
Select only distinct data from a table
SELECT DISTINCT column_name(s)
FROM table_name
Select only certain data from a table
SELECT column_name(s) FROM table_name
WHERE column operator value
AND / OR column operator value;
Select data from a table with sort the rows
SELECT column_name(s) FROM table_name
ORDER BY row_1, row_2 DESC, row_3 ASC, ...;
IN Clause
SELECT column_name(s) FROM table_name
WHERE column_name IN (value1, value2, ...);
GROUP BY Clause
SELECT col1, col2, … ,aggregate_fn(aggregate_exp)
FROM tables [WHERE conditions]
GROUP BY col1,col2, …;
HAVING Clause
SELECT col1, col2, …, aggregate_fn(aggregate_exp)
FROM tables [WHERE conditions]
GROUP BY col1, col2, ...
HAVING aggregate_fn_condition;
UPDATE Statement
SELECT Statement
DELETE Statement
Aggregate Functions
Create / Delete Database (DB)
INSERT Statement
Alias ( Temporary Name)
LEFT Join
Select <columns> From A
Left Join B on A.Key = B.Key
Select <columns> From A
Left Join B where B.Key is null
A B
A B
RIGHT Join
Select <columns> From A
Right Join B on A.Key = B.Key
Select <columns> From A
Right Join B where B.Key is null
A B
BA
OUTER Join
Select <columns> From A
Full Outer Join B on A.Key =
B.Key
Select <columns> From A
Full Outer Join B where
A.Key is null AND B.Key is null
A B
A B
INNER (Simple) Join
Select <columns> From A
INNER Join B on A.Key = B.Key
A B
UNION removes duplicate rows
SELECT col1, col2, ... colN
FROM table1[WHERE conditions]
UNION
SELECT col1, col2, ... colN
FROM table2 [WHERE conditions];
UNION ALL does not remove duplicate row
SELECT col1, col2, ... colN
FROM table1[WHERE conditions]
UNION ALL
SELECT col1, col2, ... colN
FROM table2 [WHERE conditions];
SELECT col1, col2, ... colN
FROM A [WHERE conditions]
MINUS
SELECT col1, col2, ... colN
FROM B [WHERE conditions];
A B
Create Primary Key Constraint
CREATE TABLE table_name (
column1 datatype [ NULL | NOT NULL ],…
CONSTRAINT pk_name PRIMARY KEY (pk_col1,..) ;
Add Primary Key Constraint
ALTER TABLE A ADD CONSTRAINT constraint_name
PRIMARY KEY (col1,…);
Drop Primary Key
ALTER TABLE table_name DROP PRIMARY KEY;
Create Foreign Key Constraint
CREATE TABLE table_name (
column1 datatype [ NULL | NOT NULL ], ...
CONSTRAINT fk_column FOREIGN KEY (col1, …)
REFERENCES parent_table (col1, …));
Add Foreign Key Constraint
ALTER TABLE A ADD CONSTRAINT fk_name
FOREIGN KEY (col1, …)
REFERENCES parent_table (col1, …);
Drop Primary Key
ALTER TABLE A DROP CONSTRAINT constraint_name;
Create Unique Constraint
CREATE TABLE table_name (
column1 datatype [ NULL | NOT NULL ], ...
CONSTRAINT uq_name UNIQUE (uc_col1, ... ));
Drop Unique Constraint
ALTER TABLE A DROP CONSTRAINT constraint_name;
Create Check Constraint
CREATE TABLE table_name (
column1 datatype [ NULL | NOT NULL ], ...
CONSTRAINT ck_name CHECK (col1 condition));
UNION
Column name alias
SELECT column_name AS column_alias
FROM table_name;
Table name alias
SELECT table_alias.column_name
FROM table_name AS table_alias ;
Delete rows in a table
DELETE FROM table_name
WHERE column_name = some_value;
Deletes all data inside the table
TRUNCATE TABLE table_name;
Data Types
Primary Key Constraint
Foreign Key Constraint
Unique Key Constraint
Check Constraint
MINUS
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