Oracle database

select * from sample_db where 

id =1

and 

(name like '%praveen%'

or name like '%naveen%')

SQL CONSTRAINTS

primary key

CREATE TABLE sbanks (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    PRIMARY KEY (ID)
);

TO ADD PRIMARY KEY CONSTRAINT TO EXISTING TABLE ie for one column.

 syntax

ALTER TABLE sbank

ADD PRIMARY KEY (ID);

imp:u can have primary key constraint one only.

now to add primary key constraint for more than one column to already existing table with primary constraint

you have to delete existing primary key,and add  new primary key constraint.

DROP a PRIMARY KEY Constraint

syntax
ALTER TABLE sbank
DROP PRIMARY KEY;
o/p
 MySQL returned an empty result set 

now adding primary key constraint for two columns

ALTER TABLE sbank
ADD CONSTRAINT PK_sbank PRIMARY KEY (ID,LastName)
o/p
MySQL returned an empty result set

here PK_sbank is the constraint name.

DATABASE column name search in all tables /schemas

select c.tabschema as schema_name,
       c.tabname as table_name,c.colname
from syscat.columns c
inner join syscat.tables t on 
      t.tabschema = c.tabschema and t.tabname = c.tabname
where c.colname like '%PRODUCT_NUMBER%' and t.type = 'T'

order by schema_name,table_name;

for more details https://dataedo.com/kb/query/db2/find-tables-with-specific-column-name

https://dataedo.com/kb/query/db2

SEARCH TABLES QUERY

select name from sysibm.systables 
where name like '%ISP%' 
and type = 'T'

EASY CONCATENATE STRINGS IN EXCEL AND SEARCH THE STRING IN DB

="'"&A1&"',"

DB2 

SELECT * FROM customers FETCH FIRST 1 ROWS ONLY

http://www.oracle.com/technetwork/developer-tools/sql-developer/downloads/index.html?ssSourceSiteId=otnpt

SQL joins are used to combine rows from two or more tables.

Types of Joins:

INNER JOIN: Returns all rows when there is at least one match in BOTH tables

EG: view Intersection (matching data in two tables) of two table’s data.

Syn: SELECT column_name(s) FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name;

LEFT JOIN: Return all rows from the left table, and the matched rows from the right table

EG : view Table 1’s + Intersection (matching data in two tables) of two table’s data

Syn: SELECT column_name(s) FROM table1 LEFT JOIN table2 ON table1.column_name=table2.column_name;

RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table

EG : Intersection (matching data in two tables) of two table’s data + Table 2’s

FULL JOIN: Return all rows when there is a match in ONE of the tables

EG : view complete  2 table’s data  (Table1 + Table 2)

http://dev.mysql.com/doc/refman/5.0/en/join.html

for more details https://www.javatpoint.com/dbms-normalization