import MySQLdb # 连接到MySQL数据库 conn = MySQLdb.connect(host='localhost', user='username', passwd='password', db='database') cursor = conn.cursor() # 查询表的列 cursor.execute("DESCRIBE table_name") columns = cursor.
When you have more than one column in your SQL DISTINCT statement, the SQL interpreter selects all unique combinations between those columns. In our Cars table we have two entries for Toyota (Company column) and those records both have Japan (Country column). So instead of Toyota and Japan ...
Syntax:SELECT[ALL | DISTINCT | DISTINCTROW][HIGH_PRIORITY][STRAIGHT_JOIN][SQL_SMALL_RESULT][SQL_BIG_RESULT][SQL_BUFFER_RESULT]SQL_NO_CACHE[SQL_CALC_FOUND_ROWS]select_expr[, select_expr ...][FROM table_references [PARTITION partition_list][WHERE where_condition][GROUP BY {col_name | expr ...
SQL> create table t3(id number); Table created SQL> declare 2 i number; 3 begin 4 for i in 1..3000000 loop 5 insert into t3 values (i); 6 end loop i; 7 commit; 8 end; 9 / PL/SQL procedure successfully completed Session 2: SQL> select * from v$mystat where rownum<2; 在ses...
VALUES(10),(20),(30),(40),(50) GO SELECT * FROM TestTable A database with a single table is created. The table has indexes, constraints, and contains sample data: Creating a table from another table with a computed column with SQL SELECT INTO ...
SQL Server -> 应用程序 结果处理 开发者 -> 应用程序 整体流程 步骤详解 导入数据库 在开始之前,我们首先需要导入一个数据库来测试我们的转换方法。你可以使用以下SQL语句在SQL Server中创建一个测试表: CREATETABLETestTable(ID uniqueidentifierPRIMARYKEY,Name nvarchar(50))INSERTINTOTestTable(ID,Name)VALUES('...
SQL Distinct So far we have used the select statement to retrieve all the records in a table regardless if some values repeat or not. If you wish, you can use the DISTINCT keyword to remove duplicates from your results. For instance if you wanted to just return a unique list of employees...
Here, the SQL command selects only the unique values of age from theCustomerstable. Syntax of SQL SELECT DISTINCT SELECTDISTINCTcolumn1, column2 ...FROMtable; Here, column1, column2, ...are the table columns tableis table name from where we retrieve the distinct columns ...
The SELECT UNIQUE construct is an Oracle-only SQL statement. It is equivalent to SELECT DISTINCT. SyntaxThe syntax for SELECT UNIQUE is as follows:SELECT UNIQUE "column_name" FROM "table_name";ExampleWe use the following table for our example. Table Store_Information ...
百度试题 题目SQL 语句可返回唯一不同的值的是( )。 A. SELECT ALL B. SELECT DIFFERENT C. SELECT UNIQUE D. SELECT DISTINCT 相关知识点: 试题来源: 解析 D null 反馈 收藏