A NULL column can be altered to a NOT NULL column only when it is entirely NULL or has a value for every row.
SQL Error: ORA-01441: cannot decrease column length because some value is too big
Difference between delete and truncate
How to solve ORA-28000: the account is locked?
Sequences in Oracle
Deleting duplicate records from a table
ORACLE PL/SQL INTERVIEW QUESTION : FACTORIAL PROGRAM
Difference between view and materialized view
How to solve ORA-28002: the password will expire warning
How to solve ORA-01940: cannot drop a user that is currently connected?
Debugging Oracle PL/SQL code with ORACLE SQL DEVELOPER tool
Procedures in Oracle PL/SQL
ACID properties in RDBMS database
Indexes in Oracle