[untitled] database - limit the number of returned rows

The following is the statement that the database limits the number of returned rows ,SELECT TOP Clause is used to limit the number or percentage of rows returned in the query result set . Because the order of rows stored in the table is unpredictable , therefore SELECT TOP The statement is always the same as ORDER BY Clauses are used together . result , The result set is limited to the first N Number of ordered lines . Here is the SELECT Of the statement TOP Syntax of clause ：

In this grammar , SELECT Statements can contain other clauses , Such as ： WHERE , JOIN , HAVING and GROUP BY .expression - TOP The keyword is followed by an expression , It specifies the number of rows to return . If you use PERCENT , The expression is evaluated as a floating-point value , Otherwise, convert it to BIGINT value .PERCENT - PERCENT Keyword indicates before the query returns N Percentage of rows , among N Is the result of the expression .WITH TIES - WITH TIES Used to return more rows , Its value matches the last row in the finite result set . Please note that , WITH TIES It may cause more rows to be returned than specified in the expression .

OFFSET and FETCH Clause is ORDER BY Clause options . They are used to limit the number of rows returned by the query . Must be OFFSET and FETCH Clause and ORDER BY Clauses are used together OFFSET and FETCH Clause is better than implementation TOP Clause is more suitable for implementing query paging solution. The following is OFFSET and FETCH Syntax of clause ：

In the above grammar ,OFFSET Clause specifies the number of rows to skip before starting to return rows from the query . offset_row_count It can be a constant greater than or equal to zero , Variables or parameters .

FETCH Clause specifies when processing OFFSET Number of rows to return after clause . offset_row_count Can be greater than or equal to 1 The constant , Variable or scalar .

OFFSET Clause is required , and FETCH Clauses are optional . Besides , FIRST and NEXT Synonyms , So they can be used interchangeably .