select 课程.课程编号, 课程.课程名称, 成绩.每科最高分 2.先查找出每门课程的最高分。——确定查询条件 SELECT 课程编号, MAX(成绩) FROM 成绩 GROUP BY 课程编号; 3.连接两表。确定连接主键和筛选条件。我们在第2步确定了查询条件,所以在这一步加到两表连接的筛选条件中。 select b.课程编号, b.课程...
GO SELECT * FROM TestBatch; -- Returns no rows. GO In the following example, the third INSERT statement generates a run-time duplicate primary key error. The first two INSERT statements are successful and committed, so they remain after the run-time error. SQL Copy CREA...
SELECT MAX(DepartmentID) FROM Test.Department ; -- Use the next desired value (4) as the START WITH VALUE; CREATE SEQUENCE Test.DeptSeq AS smallint START WITH 4 INCREMENT BY 1 ; GO -- Add a default value for the DepartmentID column ALTER TABLE Test.Department ADD CONSTRAINT ...
select *, sum(成绩) over (order by 学号) as current_sum, avg(成绩) over (order by...
After you determine that an index is appropriate for a query, you can select the type of index that best fits your situation. Index characteristics include the following list:Clustered versus nonclustered Unique versus nonunique Single column versus multicolumn Ascending or descending order on ...
SELECT VariantCol +@CharacterVar FROM MyTable However, by casting the sql_variant operand, you can perform the operation: SELECT CAST(VariantCol AS varchar(25)) +@CharacterVar FROM MyTable Applications and sql_variant Data If an application requests a result set in which a specific column retu...
SELECT MIN(column_name), MAX(column_name) FROM table_name; 在上述查询中,column_name是要计算最小值和最大值的列名,table_name是要查询的表名。 这种查询在很多场景下都有应用,例如统计销售订单中每个客户的最早和最晚订单日期,或者查找某个产品的最低和最高价格等。 对于腾讯云的相关产品,可以使用腾讯云...
35000 Condition number is invalid. Table 23. Class Code 36: Cursor Sensitivity Exception SQLSTATE ValueMeaning 36001 A SENSITIVE cursor cannot be defined for the specified select-statement. Table 24. Class Code 38: External Function Exception SQLSTATE ValueMeaning XXXXX Valid error SQLSTATEs retur...
Sub SelectX3() Dim dbs As Database, rst As Recordset ' Modify this line to include the path to Northwind ' on your computer.Setdbs = OpenDatabase("Northwind.mdb")' Count the number of employees, calculate the 'average salary,andreturnthe highest salary.Setrst = dbs.OpenRecordset("SELECT...
35000 Condition number is invalid. Table 23. Class Code 36: Cursor Sensitivity Exception SQLSTATE ValueMeaning 36001 A SENSITIVE cursor cannot be defined for the specified select-statement. Table 24. Class Code 38: External Function Exception SQLSTATE ValueMeaning XXXXX Valid error SQLSTATEs retur...