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How do you handle no data found exception in PL SQL?

How do you handle no data found exception in PL SQL?

For example, PL/SQL raises the predefined exception NO_DATA_FOUND if a SELECT INTO statement returns no rows. You can use the pragma EXCEPTION_INIT to associate exception names with other Oracle error codes that you can anticipate. To handle unexpected Oracle errors, you can use the OTHERS handler.

How do I handle no data found exception in Oracle stored procedure?

For example, PL/SQL raises the predefined exception NO_DATA_FOUND if a SELECT INTO statement returns no rows. To handle other Oracle errors, you can use the OTHERS handler. The functions SQLCODE and SQLERRM are especially useful in the OTHERS handler because they return the Oracle error code and message text.

What are PL SQL cursor exceptions?

An exception is an error condition during a program execution. PL/SQL supports programmers to catch such conditions using EXCEPTION block in the program and an appropriate action is taken against the error condition. There are two types of exceptions − System-defined exceptions. User-defined exceptions.

How does PL SQL handle cursor exceptions?

To handle the exception explicity, they must be declared using Pragma EXCEPTION_INIT as given above and handled referecing the user-defined exception name in the exception section. END; For Example: Lets consider the product table and order_items table from sql joins.

How do you handle exceptions in loop in PL SQL?

HANDLE EXCEPTIONS INSIDE CURSOR LOOP

  1. STEP 1: CREATE a TABLE to Capture Error Logs:
  2. STEP 2: CREATE PL/SQL Block to Handle Exception inside Cursor Loop.

How many types of exceptions are there in PL SQL?

three types

Where are exceptions used in PL SQL?

An error occurs during the program execution is called Exception in PL/SQL. PL/SQL facilitates programmers to catch such conditions using exception block in the program and an appropriate action is taken against the error condition. There are two type of exceptions: System-defined Exceptions.

What is trigger in PL SQL with examples?

Triggers are stored programs, which are automatically executed or fired when some events occur. Triggers are, in fact, written to be executed in response to any of the following events − A database manipulation (DML) statement (DELETE, INSERT, or UPDATE) A database definition (DDL) statement (CREATE, ALTER, or DROP).

How do you handle unique constraint exceptions in PL SQL?

begin merge into some_table st using (select ‘some’ name, ‘values’ value from dual) v on (st.name=v.name) when matched then update set st. value=v. value when not matched then insert (name, value) values (v.name, v.

How do you handle unique constraint error?

To handle unique constraint violations:

  1. Catch uniqueness exceptions thrown by the database at the lowest level possible — in the UnitOfWork class.
  2. Convert them into Result.

How do you catch Ora 00001 unique constraint violated?

The option(s) to resolve this Oracle error are:

  1. Option #1. Drop the unique constraint.
  2. Option #2. Change the constraint to allow duplicate values.
  3. Option #3. Modify your SQL so that a duplicate value is not created. Note.

How do you fix Ora 00001 unique constraint violated?

There are a few solutions to the “ORA-00001 unique constraint violated” error:

  1. Change your SQL so that the unique constraint is not violated.
  2. Change the constraint to allow for duplicate values.
  3. Drop the constraint from the column.
  4. Disable the unique constraint.

What is Ora 00001 unique constraint violated?

The ORA-00001 message is triggered when a unique constraint has been violated. Essentially the user causes the error when trying to execute an INSERT or UPDATE statement that has generated a duplicate value in a restricted field.

What is a unique constraint violation?

A unique constraint violation occurs when an UPDATE or INSERT statement attempts to insert a record with a key that already exists in the table. A function is attempting to add this sequence, but the value already exists in the table.

How do you drop a unique constraint?

To delete a unique constraint using Table Designer

  1. In Object Explorer, right-click the table with the unique constraint, and click Design.
  2. On the Table Designer menu, click Indexes/Keys.
  3. In the Indexes/Keys dialog box, select the unique key in the Selected Primary/Unique Key and Index list.
  4. Click Delete.

How do you drop a unique constraint in Oracle?

Drop Unique Constraint The syntax for dropping a unique constraint in Oracle is: ALTER TABLE table_name DROP CONSTRAINT constraint_name; table_name. The name of the table to modify.

Can primary key be null?

Primary key constraints A primary key defines the set of columns that uniquely identifies rows in a table. When you create a primary key constraint, none of the columns included in the primary key can have NULL constraints; that is, they must not permit NULL values. NULL values are not allowed.

Is it mandatory for the primary key to be given a value when a new record is inserted?

In practice, the primary key attribute is also marked as NOT NULL in most databases, meaning that attribute must always contain a value for the record to be inserted into the table. …

How do I set foreign key to null?

  1. you can edit database field and allow null value to be insert. –
  2. To say that a field is a foreign key means it is constrained to match a primary key in the specified table.
  3. @hardmath ..So it cannot be Null in that case (as matching makes no sense with Null values)..

Why primary key is not null?

A PRIMARY KEY column is equivalent to UNIQUE and NOT NULL and is indexed column by default. In addition a primary key may be used a FOREIGN KEY in other tables and that’s why it cannot be NULL so that the other table can fin the rows in the referenced table.

Why do we use not null?

The NOT NULL constraint enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.

How do I stop null values in SQL?

A NOT NULL constraint in SQL is used to prevent inserting NULL values into the specified column, considering it as a not accepted value for that column. This means that you should provide a valid SQL NOT NULL value to that column in the INSERT or UPDATE statements, as the column will always contain data.

Can Unique Key be a primary key?

A primary key must be unique. A unique key does not have to be the primary key – see candidate key. That is, there may be more than one combination of columns on a table that can uniquely identify a row – only one of these can be selected as the primary key. The others, though unique are candidate keys.

How many nulls are allowed in unique key?

one null

What is difference between index and primary key?

A primary key is a logical concept. The primary key are the column(s) that serves to identify the rows. An index is a physical concept and serves as a means to locate rows faster, but is not intended to define rules for the table. In SQL Server a primary key for a disk-based table is always implemented as an index.

Is a unique key?

A unique key is a set of one or more than one fields/columns of a table that uniquely identify a record in a database table. The unique key and primary key both provide a guarantee for uniqueness for a column or a set of columns.