The “Try” query shows the most recent orders and has one record per unique customer. OPEN DATABASE HOME()+"samples\northwind\northwind" SELECT customerid,orderdate,employeeid FROM orders ORDER BY 1,2 INTO CURSOR temp BROWSE LAST NOWAIT SELECT CustomerId,MAX(OrderDate) FROM Orders GROUP BY...
select id, create_date from order where user_id=123 order by create_date asc limit 1; 使用limit 1,只返回该用户下单时间最小的那一条数据即可。 此外,在删除或者修改数据时,为了防止误操作,导致删除或修改了不相干的数据,也可以在sql语句最后加上limit。 例如: update order set status=0,edit_time=...
dept_record RECORD; BEGIN cur :='SELECT * FROM departments'::REFCURSOR; LOOP FETCH cur INTO dept_record; EXIT WHEN cur%NOTFOUND; RAISE NOTICE '部门:% (人数:%)', dept_record.dept_name, dept_record.employee_count; END LOOP; END $$; 三、高级应用场景 批量数据操作 CREATE OR REPLACE PROCE...
SELECT product_id, DATE_TRUNC('day', sale_time) AS sale_date, SUM(quantity) AS total_soldFROMsales GROUP BY product_id, DATE_TRUNC('day', sale_time); 1.2 高级管理技巧 版本控制 -- 创建带版本号的视图(兼容性管理) CREATE VIEW v_employee_v2 AS SELECT id, name, department, hire_dateFRO...
SELECT * FROM [StackOverflow2010].[dbo].[Posts] WHERE CreationDate >= '2009-01-01' AND CreationDate <= '2009-12-31'; Date and Time Example Let’s look at a more realistic example. I have been working with a huge partitioned table for years. Most of the time, the date columns ar...
SELECT UPPER(last_name) || ',' || LOWER(first_name) AS new_name_format FROM patients ORDER BY first_name DESC; 2.2 SELECT后接agg型函数,也是根据group by计算得结果的(& HAVING) select day(date) as days, count(day(date)) as counts from admissions group by days #这会让上面count()都变...
using Microsoft.Data.SqlClient; class Program { static void Main() { string str = "Data Source=(local);Initial Catalog=Northwind;" + "Integrated Security=SSPI"; ReadOrderData(str); } private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, Custo...
If you also specify SPFILE, this comment will appear in the parameter file to indicate the most recent change made to this parameter. DEFERRED The DEFERRED keyword sets or modifies the value of the parameter for future sessions that connect to the database. Current sessions retain the old ...
privatestaticvoidReadOrderData(stringconnectionString){stringqueryString ="SELECT OrderID, CustomerID FROM dbo.Orders;";using(SqlConnection connection =newSqlConnection(connectionString)) { SqlCommand command =newSqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteRe...
A bcp in operation minimally requires SELECT/INSERT permissions on the target table. In addition, ALTER TABLE permission is required if any of the following conditions are true: Constraints exist and the CHECK_CONSTRAINTS hint isn't specified. Disabling constraints is the default behavior. To enable...