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find out database command=> show databases; create database: syntax=> create database database_name; create database second; select working database syntax:-use database_name; =>use second ---------------------------------------------------------- create table: syntax: create table table_name( column1 datatype, column2 datatype, column3 datatype, - column3 datatype ); exa:- create table Student( rno int, name varchar(20), address varchar(20), marks int, gender char(1)); checking table: show tables_name; => show Student; for showing table structure: syntax:desc tablename; exa :-desc Student; -------------------------------------------------------------------------- insrt data into table: seuence is manadatory. number of column =number of values 1- insert into tablename values(value1,value2,-----valueN); exa:- insert into Student values(1,'nikki','pune',56,'male'); ---------------------------- --sequence is manadory for column we given in insert stament count of column specify into insert =number of values no value for any column. 2.- insert into Tablename(column1,column2-----columnN) values(value1,value2,-----valueN); ex:- insert into Student(rno,name,marks,gender) values(2,'nikita',70,'F'); -------------------------- multiple value insert at one time syntax:- insert into tablename values(value1,value2,-----valueN),(value1,value2,-----valueN)-----(n); exam:- insert into Student values(3,'ram','satara',67,'m'), (4,'anita','nagpur',89,'F'), (5,'jashu','nagpur',90,'M'); ----------------------------------------------------------------------------------------------------- fetch all record from tables:- syntax:- selct * from tablename; exam:-select * from Student; fetch select column from table; ex;- select name,marks from Student; --------------------------------------------------------------------------------------- Contraints in sql: contraints is use for to specify rules for the data in table. 1. NOT NULL:-ensure that the column cannot have a null values: 2.UNIQUE:-ensure that all values in a column are differents. 3.CHECK:-Ensures that the values in a columns satisfies a given specific condition. 4.DEFAULT:-set a default value if value is not specified for a column. 5.PRIMARY KEY:-ensure that the values of column is NOT NULL and UNIQUE. syntax:- create table table_name( column1 datatype contraint, column2 datatype contraint, - - columnN datatype contraint ); -------------------------------------------------------------------------------------------- Drop command:- for database: is used for delete the existing sql database. syntax:- drop database Database_name example:- drop database demo1; for table: drop table command is used for the table structure delete from database. syntax:- drop table table_name example:- drop table student; ----------------------------------------------------------------------------- truncate command: is used for delete the data from tables. it is used for empty table. syntax:-tuncate table tablename; exa;- truncate table customer; ------------------------------------------------------------------------------------------- Difference between drop and trucate: Drop :-1.Drop command is use for remove table defination /table structure from database. 2. table does not exist in databse. Truncate:-1.truncate command is used for delete all rows from tables.structure remain same. 2.table is exist in databse.show empty table. ---------------------------------------------------------------------------------------- Assignment:- Create Customer table. custid primary key, name unique, address not null age age>18 gmail abc@g.com insert minimum 10 records -
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