This document provides summaries of SQL statements and concepts including:
1. Select statements with various clauses like WHERE, ORDER BY, GROUP BY, DISTINCT
2. Data definition language statements like CREATE, ALTER, DROP for databases, tables, indexes, views
3. Data manipulation language statements like INSERT, UPDATE, DELETE
4. Joins - equijoin, natural join, cross join
5. Constraints - primary key, foreign key, unique, check, default
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Sql commands
1. 1. Select
2. Select with Boolean Exp
3. Select with Numeric Exp
4. Select with Date Exp
5. Create DB
6. Drop DB
7. Use DB
8. Create tab
9. Describe tab
10. Drop tab
11. Insert record
12. Update record(s)
13. Delete record(s)
14. Like clause with Select statement
15. Top clause with Select Statement
16. Order By clause with Select Statement
17. Group By clause with Select Statement
18. Distinct clause with Select Statement
19. Default constraint
20. Identity Property
21. Unique constraint
22. Check constraint
23. Alter Table
24. Primary Key constraint
25. Foreign Key constraint
26. Index
27. Views
28. Equi-Join
29. Natural Join
30. Cross Join
1) Select statement
SELECT column1, column2, columnN FROM table_name;
SQL> SELECT * FROM customers;
SQL> SELECT customerID, customername, city FROM CUSTOMERS;
SELECT column1, column2, columnN
FROM table_name
WHERE [condition] //condition- used logical/comparison operators
SQL>SELECT * FROM OrderDetails where quantity>80;
SELECT column1, column2, columnN
FROM table_name
WHERE [condition1] AND [condition2]...AND [conditionN];
SQL>SELECT * FROM Orders where shipperID>2 and employeeID=4; //and operator
SELECT column1, column2, columnN
FROM table_name
WHERE [CONDITION|EXPRESSION];
2) Boolean Expression
SELECT column1, column2, columnN
FROM table_name
WHERE SINGLE VALUE MATCHING EXPRESSION;
SQL> SELECT * FROM CUSTOMERS WHERE City = 'Berlin';
3) Numeric Expression
SELECT numerical_expression as OPERATION_NAME
[FROM table_name
2. WHERE CONDITION];
SQL> SELECT (15 + 6) AS ADDITION;
SQL> SELECT COUNT(*) AS "No of Records" FROM CUSTOMERS;
//Built-in fns: avg(), sum()
4) Date Expression
SQL> SELECT CURRENT_TIMESTAMP;
SQL> SELECT GETDATE();
5) Create DB
CREATE DATABASE DatabaseName;
SQL> CREATE DATABASE testDB;
SQL> SHOW DATABASES;
6) Drop DB
DROP DATABASE DatabaseName;
SQL> DROP DATABASE testDB;
SQL> SHOW DATABASES;
7) Use DB
USE DatabaseName;
SQL> SHOW DATABASES;
SQL> USE testDB;
8) Create Table
CREATE TABLE table_name(
column1 datatype,
column2 datatype,
column3 datatype,
.....
columnN datatype,
PRIMARY KEY( one or more columns )
);
SQL> CREATE TABLE CUSTOMERS(
ID INT NOT NULL,
NAME VARCHAR (20) NOT NULL,
AGE INT NOT NULL,
ADDRESS CHAR (25) ,
SALARY DECIMAL (18, 2),
PRIMARY KEY (ID)
3. );
SQL> create table sample (age int, name varchar(20) default 'Tanya');
SQL> insert into sample (age) values (20);
SQL> DESC CUSTOMERS;
9) Describe Table
SQL> DESC CUSTOMERS;
10) Drop Table
DROP TABLE table_name;
SQL> DESC CUSTOMERS;
SQL> DROP TABLE CUSTOMERS;
SQL> DESC CUSTOMERS;
11) Insert Record (Specific Columns or all Columns in a Record, Populate table using another table)
INSERT INTO TABLE_NAME (column1, column2, column3,...columnN)
VALUES (value1, value2, value3,...valueN);
SQL> INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY) VALUES (6, 'Komal', 22, 'MP', 4500.00 );
INSERT INTO TABLE_NAME VALUES (value1,value2,value3,...valueN);
SQL> INSERT INTO CUSTOMERS VALUES (7, 'Muffy', 24, 'Indore', 10000.00 );
INSERT INTO first_table_name [(column1, column2, ... columnN)]
SELECT column1, column2, ...columnN
FROM second_table_name
[WHERE condition];
12) Update Record(s)
UPDATE table_name
SET column1 = value1, column2 = value2...., columnN = valueN
WHERE [condition];
SQL> UPDATE CUSTOMERS SET ADDRESS = 'Pune' WHERE ID = 6;
UPDATE table_name
SET column1 = value1, column2 = value2...., columnN = valueN;
SQL> UPDATE CUSTOMERS SET ADDRESS = 'Pune', SALARY = 1000.00;
13) Delete Record(s)
DELETE FROM table_name
WHERE [condition];
SQL> DELETE FROM CUSTOMERS WHERE ID = 6;
DELETE FROM table_name;
4. SQL> DELETE FROM CUSTOMERS;
14) Like clause with Select statement
Finds any values that start with XXXX
SELECT FROM table_name WHERE column LIKE 'XXXX%';
SELECT * FROM Customers where postalcode like '0%';
Finds any values that end with XXXX
SELECT FROM table_name WHERE column LIKE '%XXXX';
SELECT * FROM Customers where postalcode like '%3';
Finds any values that have XXXX in any position
SELECT FROM table_name WHERE column LIKE '%XXXX%';
SELECT * FROM Products where productname like '%bo%';
Finds any values that have XXXX in certain positions
SELECT FROM table_name WHERE column LIKE '_XXXX%';
SELECT * FROM Suppliers where phone like '_1%';
SELECT * FROM Suppliers where phone like '_1%2';
15) Top clause with Select Statement to fetch few records
SELECT TOP number|percent column_name(s)
FROM table_name
WHERE [condition]
SQL> SELECT TOP 3 * FROM CUSTOMERS;
SQL> SELECT * FROM CUSTOMERS LIMIT 3; //MySQL
SQL> SELECT * FROM CUSTOMERS WHERE ROWNUM <= 3; //Oracle
16) Order By clause with Select Statement to sort
SELECT column-list
FROM table_name
[WHERE condition]
[ORDER BY column1, column2, .. columnN] [ASC | DESC];
SQL> SELECT * FROM CUSTOMERS order by country, city; // Ascending order is default
SELECT * FROM CUSTOMERS order by country, city DESC;
17) Group By clause with Select Statement to arrange identical data into groups
SELECT column1, column2
FROM table_name
WHERE [ conditions ]
GROUP BY column1, column2
ORDER BY column1, column2
SQL> SELECT * FROM OrderDetails order by ProductID;
SQL> SELECT ProductID, SUM(Quantity) FROM OrderDetails GROUP BY ProductID;
SQL> SELECT ProductID, SUM(Quantity) FROM OrderDetails GROUP BY ProductID order by
Sum(Quantity);
5. 18) Distinct clause with Select Statement to eliminate all the duplicate records and
fetching only unique records
SELECT DISTINCT column1, column2,.....columnN
FROM table_name
WHERE [condition]
SQL> SELECT * FROM Suppliers order by Country;
SQL> SELECT Distinct Country, SupplierName, ContactName, City, Phone FROM Suppliers
order by Country;
19) DEFAULT constraint
SQL> CREATE TABLE users (NAME char(20), AGE integer,
PROFESSION varchar(30) DEFAULT "Student");
SQL>INSERT INTO users (NAME, AGE) VALUES ('ALAN', 36);
SQL> CREATE TABLE users (NAME char(20), AGE integer,
PROFESSION varchar(30) DEFAULT "Student");
SQL>INSERT INTO users (NAME, AGE) VALUES ('ALAN', 36);
SQL> CREATE TABLE Order21 (
ID int NOT NULL,
OrderNumber int NOT NULL,
OrderDate date DEFAULT GETDATE()
);
SQL> INSERT INTO Order21 (ID, OrderNumber) VALUES (20, 201);
20) IDENTITY property OF COLUMN
SQL> CREATE TABLE dept (DEPTNO smallint NOT NULL IDENTITY (500, 1),
DEPTNAME varchar(36) NOT NULL, DEPTID smallint NOT NULL, LOCATION char(30));
SQL> INSERT INTO dept (DEPTNAME, DEPTID) VALUES ('MECH', 20);
SQL> INSERT INTO dept (DEPTNAME, DEPTID, LOCATION) VALUES ('CSE', 10, 'INDIA');
21) UNIQUE constraint
SQL> CREATE TABLE Persons (ID int NOT NULL UNIQUE,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int);
SQL> INSERT INTO Persons (ID, LastName, Age) VALUES (100, 'BROWN', 20);
SQL> INSERT INTO Persons (ID, LastName, Age) VALUES (100, 'RED', 20); ………………ERROR
22) Check constraint
SQL> CREATE TABLE employee (ID integer NOT NULL,
NAME varchar(9),
DEPT smallint CHECK (DEPT BETWEEN 10 AND 100),
JOB char(5) CHECK (JOB IN ('Sales', 'IT', 'Clerk')),
HIREDATE DATE, SALARY DECIMAL(7,2),
CONSTRAINT YEARSAL CHECK (YEAR(HIREDATE) > 2000 OR SALARY>10000)
);
6. SQL> INSERT INTO employee (ID, DEPT, JOB, HIREDATE, SALARY)
VALUES (100, 55, 'Sales', 1995, 12000);
SQL> INSERT INTO employee (ID, DEPT, JOB, HIREDATE, SALARY)
VALUES (100, 55, 'Sales', 1995, 9000); ………………ERROR
SQL> INSERT INTO employee (ID, DEPT, JOB, HIREDATE, SALARY)
VALUES (100, 200, 'Sales', 1995, 9000); ………………ERROR
SQL> INSERT INTO employee (ID, DEPT, JOB, HIREDATE, SALARY)
VALUES (100, 200, ‘Sale', 1995, 9000); ………………ERROR
23) Alter table
SQL> CREATE TABLE employee (ID integer NOT NULL,
NAME varchar(9),
DEPT smallint CHECK (DEPT BETWEEN 10 AND 100),
JOB char(5) CHECK (JOB IN ('Sales', 'IT', 'Clerk')),
HIREDATE DATE, SALARY DECIMAL(7,2),
CONSTRAINT YEARSAL CHECK (YEAR(HIREDATE) > 2000 OR SALARY>10000)
);
SQL> ALTER TABLE employee DROP COLUMN NAME;
SQL> ALTER TABLE employee ADD COLUMN NAME varchar(9);
24) Primary Key Constraint
SQL> CREATE TABLE personnel (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
SQL> CREATE TABLE personnel1 (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);
25) Foreign Key Constraint
SQL> CREATE TABLE personnel (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
SQL> CREATE TABLE Order (
OrderID int NOT NULL PRIMARY KEY,
OrderNumber int NOT NULL,
ID int FOREIGN KEY REFERENCES personnel(ID)
);
7. 26) Index Constraint
SQL> CREATE INDEX index_id ON Order21 (ID);
27) Views
SQL> CREATE TABLE personnel (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
SQL> INSERT INTO personnel (ID, LastName, FirstName, Age)
VALUES (10, 'BROWN', 'TIM', 28);
SQL> CREATE VIEW myview1 AS SELECT ID, FirstName FROM personnel;
SQL> SELECT * FROM myview1;
28)Equi-Join
Select * FROM student, enrollment
WHERE student.enrollment_no = enrollment.enrollment_no;
(or)
Select * FROM student
INNER JOIN enrollment
ON student.enrollment_no = enrollment.enrollment_no;
29) Natural Join
SELECT *
FROM student
NATURAL JOIN enrollment;
30) Cross Join
SELECT *
FROM student, enrollment;