Explicitly checking if an SQL INSERT operation succeeded unnecessary?
I'm using Python to talk to a Postgres DBMS using psycopg2.
Is it safe to assume that if an INSERT returns without raising an exception, then that INSERT actually did store something new in the database?
Right now, I've been checking the 'rowcount' attribute of the database cursor, and if it's 0 then that means the INSERT failed. However, I'm starting to think that this isn't necessary.
Performing SQL Operations from PL/SQL, Example 6-2 Checking SQL%ROWCOUNT After an UPDATE If you want precise control over query processing, you can declare an explicit cursor In Example 6-7, you use %FOUND to insert a row if a delete succeeds. After such a statement, the %NOTFOUND attribute is always FALSE , so checking it is unnecessary. 1 Explicitly checking if an SQL INSERT operation succeeded unnecessary? Feb 25 '19. 1 Printing lists in python gives unwanted output Apr 8 '19.
found similar question here, How to check if value is inserted successfully or not?
they seem to use the row count method to check if the data was inserted correctly.
Methods to Insert Data into SQL Server, Insert Data into SQL Server Using an Explicit Column List With a default constraint on the column, we may test another INSERT where we This statement executes successfully, despite no column list being provided. When SQL Server binds this query to its underlying objects, it will pull the column list in � I have a stored procedure. After insert, it should return a value: if the insert was successful, then return 1, else return 0. For example: ALTER PROCEDURE [dbo].[sp_save_transaction] -- Par
postgres will return
None for a successful insert:
cursor.execute- The method returns
None. If a query was executed, the returned values can be retrieved using fetch*() methods.
If you want to know something about the insert, an easy/efficient option is to use
RETURNING (which takes the same options as a
INSERT INTO ... RETURNING id
SQL INSERT Statement in a bit more detail, Now that you have installed MySQL we will explore the SQL INSERT What follows is intuitive – the VALUES keyword, succeeded by the same To register this row in the data table, we'll need to execute the INSERT query. When data is being created to test the database system, the value inserted should be quite high. The INSERT OR UPDATE statement is a variant of the INSERT statement that performs both insert and update operations. First it attempts to perform an insert operation. If the insert request fails due to a UNIQUE KEY violation (for the field(s) of some unique key, there exists a row that already has the same value(s) as the row specified for the insert), then it automatically turns into an
Documentation: 9.1: Basic Statements, For any SQL command that does not return rows, for example INSERT without a PL/pgSQL variables will be substituted into the query just as for commands that You can check the special FOUND variable (see Section 39.5.5) to determine will never succeed if keyvalue is null, because the result of using the equality� The INSERT OR UPDATE statement is a variant of the INSERT statement that performs both insert and update operations. First it attempts to perform an insert operation. If the insert request fails due to a UNIQUE KEY violation (for the field(s) of some unique key, there exists a row that already has the same value(s) as the row specified for the insert), then it automatically turns into an
Documentation: 9.3: CREATE TABLE, A constraint is an SQL object that helps define the set of valid values in the table in If the new table explicitly specifies a default value for the column, this default CHECK constraints are merged in essentially the same way as columns: if new or updated rows must satisfy for an insert or update operation to succeed. Warning: Null value is eliminated by an aggregate or other SET operation. Let us run below script in SQL Server Management Studio to see the effect. SET NOCOUNT ON GO DECLARE @ItemSale TABLE (ID INT, Qty INT, Price MONEY) INSERT INTO @ItemSale (ID, Qty, Price) SELECT 1, 25, 100 INSERT INTO @ItemSale (ID, Qty, Price) SELECT 2, NULL, 200
Additional Persistence Techniques — SQLAlchemy 1.3 , This technique works both for INSERT and UPDATE statements. After the flush/ commit operation, the value attribute on someobject above is expired, the primary key value on INSERT, to be successfully retrieved by the ORM as part of the bar = Column(Integer) e = create_engine("postgresql://scott:tiger@ localhost/test",� Managing Cursors in PL/SQL. PL/SQL uses implicit and explicit cursors. PL/SQL declares a cursor implicitly for all SQL data manipulation statements, including queries that return only one row. If you want precise control over query processing, you can declare an explicit cursor in the declarative part of any PL/SQL block, subprogram, or package.