or more columns in one table are equal to one or more columns in the second table.
What are various constraints used in SQL ?
NULL, NOT NULL, CHECK, DEFAULT
What are different Oracle database objects ?
TABLES, VIEWS, INDEXES, SYNONYMS, SEQUENCES, TABLESPACES etc
What is difference between Rename and Alias ?
Rename is a permanent name given to a table or column whereas Alias is a temporary
name given to a table or column which do not exist once the SQL statement is executed.
What is a view ?
A view is stored procedure based on one or more tables, it's a virtual table.
What are various privileges that a user can grant to another user ?
SELECT, CONNECT, RESOURCES
What is difference between UNIQUE and PRIMARY KEY constraints ?
A table can have only one PRIMARY KEY whereas there can be any number of UNIQUE
keys. The columns that compose PK are automatically define NOT NULL, whereas a column that
compose a UNIQUE is not automatically defined to be mandatory must also specify the column is
NOT NULL.
Can a primary key contain more than one columns ?
Yes
How you will avoid duplicating records in a query ?
By using DISTINCT
What is difference between SQL and SQL*PLUS ?
SQL*PLUS is a command line tool where as SQL and PL/SQL language interface and
reporting tool. Its a command line tool that allows user to type SQL commands to be executed
directly against an Oracle database. SQL is a language used to query the relational
database(DML,DCL,DDL). SQL*PLUS commands are used to format query result, Set options,
Edit SQL commands and PL/SQL.
Which datatype is used for storing graphics and images ?
LONG RAW
data type is used for storing BLOB's (binary large objects).
How will you delete duplicating rows from a base table ?
DELETE FROM
table_name A WHERE rowid>(SELECT min(rowid) from table_name B where
B.table_no=A.table_no);
CREATE TABLE
new_table AS SELECT DISTINCT * FROM old_table;
DROP
old_table
RENAME
new_table TO old_table
DELETE FROM table_name A
WHERE rowid NOT IN (SELECT MAX(ROWID) FROM table_name
GROUP BY column_name)
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