SQL的ORDER BY关键字用于对结果集进行排序,您可以按升序(ASC)或降序(DESC)进行排序。以下是ORDER BY关键字的基本语法: 代码语言:sql AI代码解释 SELECTcolumn1,column2,...FROMtable_nameORDERBYcolumn1,column2,...ASC|DESC; column1,column2,等是您要选择的列名称。 table_name是您从中选择记录的表的名称。
SQL入门之Select数据提取与SQL书写规则答案如下：Select数据提取关键点： 列选择：明确指定需提取的字段，例如”SELECT column1, column2 FROM table;“。 表选择：定义数据来源，如”FROM table;“。 查询条件：通过WHERE子句设置过滤规则，例如”WHERE condition;“，以...
SQL SELECT语句用于从表中选取符合条件的数据，该数据以临时表的形式返回，称为结果集。以下是关于SQL SELECT语句选取数据的详细解释：基本语法：SELECT column1, column2, columnN FROM table_name WHERE conditions;column1, column2, columnN：表示要选取的列名。table_name：表示数据所在的表名。condit...
SELECT用于从表或视图中读取数据。SELECT语句就像叠加在数据库表上的过滤器,利用SQL关键字从数据表中过滤出用户需要的数据。SELECT支持普通表和HDFS的Join,不支持普通表和GDS外表的join。即SELECT语句中不能同时出现普通表和GDS外表。必须对每个在SELECT命令中使用的字段
SELECT CONCAT(LastName,', ',FirstName) AS fullname FROM employeesCode language: SQL (Structured Query Language) (sql) An SQL alias is used to format the output in this example. Summary Use the SELECT statement to query data from a table. Specify one or more column names after the SELECT...
Complex Column Expressions Do Math with SQL SELECT! SQL Distinct Practical uses of SQL SELECT DISTINCT Finding and Correcting SQL Select Errors SQL Select Exercises Understanding Your Database A simple select statement consists of two parts. The first part describes what columns we want to view and...
syntaxsql [WITH<common_table_expression>[ , ...n ] ]SELECT<select_criteria>[ ; ]<select_criteria>::=[TOP(top_expression) ] [ALL|DISTINCT] { * |column_name| expression } [ , ...n ] [FROM{table_source} [ , ...n ] ] [WHERE<search_condition>] [GROUPBY<group_by_clause>] [HA...
You can display the structure of a table by using the DESCRIBE command. The command displays the column names and the data types, and it shows you whether a column must contain data(that is, whether the column has a NOT NULL constraint.) ...
columnN datatype,PRIMARYKEY(oneormore columns ) ); 写法1: test=#createtablecompany(idintprimarykeynotnull, name textnotnull, ageintnotnull,addresschar(50) , salaryreal); 写法2: test=#CREATETABLECOMPANY( test(# IDINTPRIMARYKEYNOTNULL, ...
ExampleGet your own SQL Server Return data from the Customers table: SELECTCustomerName, CityFROMCustomers; Try it Yourself » Syntax SELECTcolumn1,column2, ... FROMtable_name; Here, column1, column2, ... are thefield namesof the table you want to select data from. ...