Published: 23.11.2017 10:19

Sql server dynamic sql update statement

«Sql server dynamic sql update statement» in pictures.

Generating Insert or Update statements from table data using SQL

OPTIMISTIC
Specifies that positioned updates or deletes made through the cursor do not succeed if the row has been updated since it was read into the cursor. SQL Server does not lock rows as they are read into the cursor. It instead uses comparisons of timestamp column values, or a checksum value if the table has no timestamp column, to determine whether the row was modified after it was read into the cursor. If the row was modified, the attempted positioned update or delete fails. OPTIMISTIC cannot be specified if FAST_FORWARD is also specified.

The Curse and Blessings of Dynamic SQL

Can you create new record
Hi, i like to know how to create new record after the fourth records? Using the CLR routine?

Execution Plan Caching and Reuse

For information about MS DTC, see the Guide to Microsoft Distributed Transaction Coordinator, which includes a sample ODBC SQL Server MS DTC application.

This script can be easily expanded to take in more complex situations, such as generating a list of update statements for a table (although a delete all/insert might be better?), or for dealing with multiple primary keys, or for partial matching across primary keys. I also considered making the script detect the primary key automatically, but this adds a lot of complexity for very little benefit.

length limit
It works well and is an elegant solution, but when the result is more 755, the rest is cut off. Any idea how to work around this?

When memory pressure exists, the Database Engine responds by removing execution plans from the procedure cache. To determine which plans to remove, the Database Engine repeatedly examines the state of each execution plan and removes plans when their current cost is zero. An execution plan with zero current cost is not removed automatically when memory pressure exists it is removed only when the Database Engine examines the plan and the current cost is zero. When examining an execution plan, the Database Engine pushes the current cost towards zero by decreasing the current cost if a query is not currently using the plan.

SCROLL
Specifies that all fetch options (FIRST, LAST, PRIOR, NEXT, RELATIVE, ABSOLUTE) are available. If SCROLL is not specified in an ISO DECLARE CURSOR, NEXT is the only fetch option supported. SCROLL cannot be specified if FAST_FORWARD is also specified.

sp_executesql can be used instead of stored procedures to execute a Transact-SQL statement many times when the change in parameter values to the statement is the only variation. Because the Transact-SQL statement itself remains constant and only the parameter values change, the SQL Server query optimizer is likely to reuse the execution plan it generates for the first execution.

SQL Server still requests a shared lock on each row as it is read into the cursor as in READ COMMITTED, but if the cursor is opened within a transaction, the shared locks are held until the end of the transaction instead of being freed after the row is read. This is the same effect as specifying HOLDLOCK on a SELECT statement.

SQL Server acquires a shared lock while reading a row into a cursor but frees the lock immediately after reading the row. Because a shared lock request is blocked by an exclusive lock, a cursor is prevented from reading a row that another task has updated but not yet committed.