上面代码使用SELECT TOP 5语句,只检索前 5 行数据。 如果你使用的是 DB2,就得使用下面这样的 DB2 特有的 SQL 语句: SELECTprod_name FROMProducts FETCHFIRST5ROWSONLY; FETCH FIRST 5 ROWS ONLY就会按字面的意思去做的(只取前 5 行)。 如果你使用 Oracle,需要基于ROWNUM(行计数器)来计算行,像这样: SELECT...
SELECT * FROM Customers WHERE Country='Germany' FETCH FIRST 3 ROWS ONLY; 添加ORDER BY 关键字 在要对结果进行排序并返回排序后结果的前 3 条记录时,添加 ORDER BY 关键字。 对于SQL Server 和 MS Access: 代码语言:sql 复制 按CustomerName 字母降序排序结果,并返回前 3 条记录: SELECT TOP 3 * FROM...
When we are working in an SQL database, we may come across instances where we need to fetch a specific subset of rows from a given table. This allows us to limit the resources needed to fetch the values from the table. Luckily, in SQL, we have access to the LIMIT clause which allows...
view, or materialized view. Oracle Database returns a set of column in the order in which the columns were specified when the object was created. A query that selects rows from two or more tables, views, or materialized views is a join. ...
SQL TOP Clause TheTOPkeyword is used in place ofLIMITwith the following database systems: SQL Server MS Access Let's look at an example. SELECTTOP2first_name, last_nameFROMCustomers; Here, the SQL command selectsfirst_nameandlast_nameof the first2rows. ...
LIMIT3; Try it Yourself » The following SQL statement shows the equivalent example for Oracle: Example SELECT*FROMCustomers ORDERBYCustomerNameDESC FETCHFIRST3ROWS ONLY; Exercise? What would the following query do in SQL Server? SELECT TOP 5 * FROM Customers; ...
SELECT Count(*) FROM Sales.Customer TABLESAMPLE(200 ROWS); GO 30 SELECT #Result.TheOrder, #Result.TheRowsReturned FROM #Result; 清单3 使用TOP…ORDER BY获取有意义的表样本 到目前为止,由于TABLESAMPLE已损坏,因此从表中获取样品的做法有些尴尬。
FETCH FIRST 6 ROWS ONLY 检索按照工资从高到低排序检索从第六名开始一共三个人的信息，那么就可以首先将前五名的主键取出来，在检索的时候检索排除了这五名员工的前三个人，SQL如下：SELECT * FROM T_Employee WHERE FNumber NOT IN (SELECT FNumber FROM T_Employee ORDER BY FSalary DESC FETCH...
SQL 执行计划 执行计划算子 SELECT INTO 更新时间:2024-10-10 23:00:01 SELECT INTO算子用于将查询结果赋值给变量列表,查询仅返回一行数据。 如下示例查询中,SELECT输出列为COUNT(*)和MAX(c1),其查询结果分别赋值给变量@a和@b。 obclient>CREATETABLEt1(c1INT,c2INT);Query OK,0rowsaffected obclient>INSERTIN...
是指在SQL查询语句中,将一个SELECT语句嵌套在另一个SELECT语句的列中。这种嵌套查询可以用来从一个表中选择特定的数据,并将其作为另一个查询的一部分进行进一步的处理和筛选。 嵌入在每行中的SELECT子句可以用于实现复杂的数据查询和分析。它可以在查询结果中生成新的计算字段,根据特定条件进行过滤,或者对查询结果进行...