For backward compatibility, the parentheses are optional in SELECT statements if the expression is an integer constant. The TOP expression doesn't affect statements that might run because of a trigger. SQL Server allows for updating rows through views. Because you can include the TOP clause in the view definition, certain rows may disappear from the view if the rows no longer meet the requirements of the TOP expression due to an update.
And, the joined rows that don't qualify for an insert, update, or delete action are removed. The TOP clause further reduces the number of joined rows to the specified value and the insert, update, or delete actions apply to the remaining joined rows in an unordered way. That is, there's no order in which the rows are distributed among the actions defined in the WHEN clauses.
For example, if specifying TOP 10 affects 10 rows, of these rows, seven may be updated and three inserted. Or, one may be deleted, five updated, and four inserted, and so on. In this scenario, it's important to ensure that all successive batches target new rows. It's possible to write a query that returns unexpected results because the order in which the TOP and ORDER BY clauses are logically processed isn't always intuitive when these operators are used in a select operation.
For example, given the following table and data, assume that you want to return the least expensive red car and the least expensive blue car.
That is, the red sedan and the blue van. So, the previous query returns any one red car and any one blue car and then orders the result of that union by the price. The following example shows the correct method of writing this query to achieve the desired result.
See the following Examples section in this article. The following examples use a constant value to specify the number of employees that are returned in the query result set. Since this question was asked first, wouldn't the other question be the duplicate? See: Should I flag a question as duplicate if it has received better answers? Bigballs since the accepted answer is wrong and extremely inefficient — Panagiotis Kanavos. Add a comment. Active Oldest Votes. Improve this answer.
Leon Tayson Leon Tayson 4, 7 7 gold badges 34 34 silver badges 35 35 bronze badges. The 2nd query fails if you have e.
It gives you rows 5 through 14, but you want rows 11 through In general, it fails for the last "page" of a result, unless the total rows are a multiple of that "page" size. Such a simple thing needs to be made so difficult by MS yet again!
This is not a good answer for any of the current SQL Server versions. Clunky, but it'll work. Do you have another suggestion to bypass this? Not pleasant, but it works. This solution works only if the result set includes a column that is unique. I'm in a similar quandary right now However, in my case I'm hosed It's even more criminal when so called 'expert' dba's decide that an unique key in unnecessary in a table ANY table Don't even bring up the subject of foreign keys and constraints!
I'm going to try temp tables, as its not working for me. HoldOffHunger Using 'with' only needs half the time to finish querying - see the answer of Leon Tayson. I have no idea what Microsoft did to make it that slow.
Why is this not the accepted answer? We are in for crying out loud! Skipper right. Let's just upvote this one to reflect the update.
That query will scan and lock the entire table — Panagiotis Kanavos. Jeremy Jeremy 1 1 gold badge 4 4 silver badges 14 14 bronze badges. Identity columns cannot be updated. When referencing the Unicode character data types nchar , nvarchar , and ntext , 'expression' should be prefixed with the capital letter 'N'.
If 'N' is not specified, SQL Server converts the string to the code page that corresponds to the default collation of the database or column. Any characters not found in this code page are lost.
This can also be used to change the column to NULL if the column has no default and is defined to allow null values. Only columns of varchar max , nvarchar max , or varbinary max can be specified with this clause. Offset is a zero-based ordinal byte position, is bigint , and cannot be a negative number.
If Offset plus Length exceeds the end of the underlying value in the column, the deletion occurs up to the last character of the value. Length is the length of the section in the column, starting from Offset , that is replaced by expression. Length is bigint and cannot be a negative number.
If the object being updated is the same as the object in the FROM clause and there is only one reference to the object in the FROM clause, an object alias may or may not be specified. If the object being updated appears more than one time in the FROM clause, one, and only one, reference to the object must not specify a table alias. All other references to the object in the FROM clause must include an object alias.
In particular, filter or join conditions applied on the result of one of those calls have no effect on the results of the other. The update operation occurs at the current position of the cursor. The search condition can also be the condition upon which a join is based. There is no limit to the number of predicates that can be included in a search condition. A searched update modifies multiple rows when the search condition does not uniquely identify a single row.
The cursor must allow updates. Use caution when specifying the FROM clause to provide the criteria for the update operation. It is undefined which row from Table2 is to be used to update the row in Table1.
Avoid using these hints in this context in new development work, and plan to modify applications that currently use them. All char and nchar columns are right-padded to the defined length. These strings are truncated to an empty string. This can be configured in ODBC data sources or by setting connection attributes or properties. Modifying a text , ntext , or image column with UPDATE initializes the column, assigns a valid text pointer to it, and allocates at least one data page, unless the column is being updated with NULL.
If the UPDATE statement could change more than one row while updating both the clustering key and one or more text , ntext , or image columns, the partial update to these columns is executed as a full replacement of the values.
Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar max , varchar max , and varbinary max instead. Use the. WRITE expression , Offset , Length clause to perform a partial or full update of varchar max , nvarchar max , and varbinary max data types. For example, a partial update of a varchar max column might delete or modify only the first bytes of the column characters if using ASCII characters , whereas a full update would delete or modify all the data in the column.
WRITE updates that insert or append new data are minimally logged if the database recovery model is set to bulk-logged or simple. Minimal logging is not used when existing values are updated.
You cannot use the. Offset and Length are specified in bytes for varbinary and varchar data types and in byte-pairs for the nvarchar data type.
For best performance, we recommend that data be inserted or updated in chunk sizes that are multiples of bytes. If the column modified by the. See example R that follows. To achieve the same functionality of. Supplying a value in a SQL Server system data type, as long as the user-defined type supports implicit or explicit conversion from that type.
The following example shows how to update a value in a column of user-defined type Point , by explicitly converting from a string. Invoking a method, marked as a mutator, of the user-defined type, to perform the update. The following example invokes a mutator method of type Point named SetXY. This updates the state of the instance of the type.
SQL Server returns an error if a mutator method is invoked on a Transact-SQL null value, or if a new value produced by a mutator method is null. Modifying the value of a registered property or public data member of the user-defined type.
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