How do I get the current date in SQL Developer?

How do I get the current date in SQL Developer?

CURRENT_DATE returns the current date in the session time zone, in a value in the Gregorian calendar of datatype DATE. The following statement shows the current date in ‘DD-MON-YYYY HH24:MI:SS’ format : SQL> ALTER SESSION SET NLS_DATE_FORMAT = ‘DD-MON-YYYY HH24:MI:SS’; Session altered.

How do you drop a foreign key constraint in SQL Developer?

Oracle / PLSQL: Drop a Foreign Key

1. Description. Once a foreign key has been created, you may find that you wish to drop the foreign key from the table.
2. Syntax. The syntax to drop a foreign key in Oracle/PLSQL is: ALTER TABLE table_name DROP CONSTRAINT constraint_name;
3. Example. If you had created a foreign key as follows:

How do I delete a foreign key in Oracle?

Dropping Foreign Key Constraints You can drop a foreign key constraint using the following ALTER TABLE syntax: ALTER TABLE tbl_name DROP FOREIGN KEY fk_symbol ; If the FOREIGN KEY clause defined a CONSTRAINT name when you created the constraint, you can refer to that name to drop the foreign key constraint.

What is enable and disable foreign key constraint in Oracle?

Oracle / PLSQL: Disable a foreign key

1. Description. Once you have created a foreign key in Oracle, you may encounter a situation where you are required to disable the foreign key.
2. Syntax. The syntax to disable a foreign key in Oracle/PLSQL is: ALTER TABLE table_name DISABLE CONSTRAINT constraint_name;
3. Example.

How can we find out the current date and time in Oracle?

SYSDATE returns the current date and time set for the operating system on which the database resides. The datatype of the returned value is DATE , and the format returned depends on the value of the NLS_DATE_FORMAT initialization parameter. The function requires no arguments.

How do I select a date in SQL?

SQL Server GETDATE() Function The GETDATE() function returns the current database system date and time, in a ‘YYYY-MM-DD hh:mm:ss.

Can foreign key be null in Oracle?

Short answer: Yes, it can be NULL or duplicate. I want to explain why a foreign key might need to be null or might need to be unique or not unique. First remember a Foreign key simply requires that the value in that field must exist first in a different table (the parent table). That is all an FK is by definition.

Can we have two foreign keys in a table in Oracle?

You could try this: CREATE TABLE ref1 ( id VARCHAR2(3) PRIMARY KEY ); CREATE TABLE ref2 ( id VARCHAR2(3) PRIMARY KEY ); CREATE TABLE look ( p VARCHAR2(3), CONSTRAINT fk_p_ref1 FOREIGN KEY (p) REFERENCES ref1(id), CONSTRAINT fk_p_ref2 FOREIGN KEY (p) REFERENCES ref2(id) );

Can foreign key be null?

Can we delete foreign key?

You can delete a foreign key constraint in SQL Server by using SQL Server Management Studio or Transact-SQL. Deleting a foreign key constraint removes the requirement to enforce referential integrity.

Can we disable index in Oracle?

To disable an index, you run an ALTER INDEX command: ALTER INDEX index_name ON table_name DISABLE; You can replace the index_name with the name of your index, and the table_name with the name of the table that the index is created on. This will disable the index on your database.

Why might you want to disable and then re-enable a constraint?

Why might you want to disable and then re-enable a constraint? Generally to make bulk operations fast, where my input data is diligently sanitized and I am sure, it is safe to save some time in this clumsy process. 12. Query the data dictionary for some of the constraints that you have created.