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What is correlated sub-query ?
Correlated sub query is a sub query which has reference to the main query.
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What is the Subquery ?
Sub query is a query whose return values are used in filtering conditions of the main query.
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What is ON DELETE CASCADE ?
When ON DELETE CASCADE is specified ORACLE maintains referential integrity by automatically removing dependent foreign key values if a referenced primary or unique key value is removed.
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List all customer (user id, name, and e-mail), number of charging
List all customer (user id, name, and e-mail), number of charging, total charging,number of transaction and total number of transaction value?If u have these tables:1- 'Credit_card'columns: credit_number,type,value,Customer_ID.2-'Coupon'columns: Coupon_number,value,password,Customer_ID3-'Customer'columns: Customer_ID,Fname,Mname,lname,E_mail,password,bdate,tot_trans,mobil_no,hom_no,ex_id_date,current_Balance.
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What is difference between CHAR and VARCHAR2 ? What is the maximum SIZE allowed for each type ?
CHAR pads blank spaces to the maximum length. VARCHAR2 does not pad blank spaces. For CHAR it is 255 and 2000 for VARCHAR2.
SQL*Plus interview Questions
Ans