SQL Syntax - more about SQL

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1. SQL SELECT INTO Statement

-- copy one table into a new tableSELECT *INTO newtable [IN externaldb]FROM table1

-- copy only columns into the new tableSELECT colName(s)INTO newtable [IN externabdb]FROM table1;

2. SQL INSERT INTO SELECT statement

-- copy data from one table and insert itinto an existing tableINSERT INTO table2SELECT * FROM table1; INSERT INTO table2 (colnames)SELECT colnames


3. SQL CREATE DATABASE statement
-- Create a databaseCREATE DATABASE dbname;

4. SQL CREATE TABLE statement
--Create a table in a databaseCREATE TABLE table_name(colname1 data_type(size),colname2 data_type(size),....);
5. SQL Constraints
--SQL constraint SyntaxCREATE TABLE table_name(column_name1 data_type(size) constraint_name,column_name2 data_type(size) constraint_name,....);

Constraints are followings:
 
NOT NULL - Indicates that a column cannot store NULL valueUNIQUE - Ensures that each row for a column must have a unique valuePRIMARY KEY - A combination of a NOT NULL and UNIQUE. Ensures that a column (or combination of two or more columns) have an unique identity which helps to find a particular record in a table more easily and quicklyFOREIGN KEY - Ensure the referential integrity of the data in one table to match values in another tableCHECK - Ensures that the value in a column meets a specific conditionDEFAULT - Specifies a default value when specified none for this column

6. SQL CREATE INDEX Statement
Index: created in a table to search/query data more quickly and efficiently.  
CREATE INDEX (UNIQUE) index_nameON table_name (colname)

7. DROP Statement
--DROP INDEX statement is used to delete an index in a table. --DROP index for SQL SERVERDROP INDEX table_name.index_name--DROP index for MySQLALTER TABLE table_name DROP INDEX index_name

-- DROP databaseDROP DATABASE database_name;

--DROP TABLE StatementDROP TABLE table_name
-- only delete the data inside the tableTRUNCATE TABLE table_name


8. SQL ALTER TABLE Statement--used to add, delete, or modify columns in an existing table.
--add column in a tableALTER TABLE table_nameADD column_name datatype--delete a columnALTER TABLE table_nameDROP COLUMN column_name

9. SQL AUTO INCREMENT Field
-- Auto-increment allows a unique number to be generated when a new record is inserted into a table.





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