group by name

One: Row to column Mode: N row to a column of this experiment n take 3 1. Table Building Sql> CREATE TABLE grade (ID int,name varchar2 (a), subject varchar2 (a), Grade number (3)); 2. Insert experimental data Insert into grade values (1, ' Andy '

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AVG (average) count (count) max (max) min (minimum) SUM (summation) The syntax for applying a function is: selecte "function name" ("Column name") from "table name1.AVG:Select AVG (Grade) from Table1, return result: Average of Grade column in Table12

--Note: rownum and ROWID only Oracle, other databases are not supportedSELECT * from Scott.dept;--the result of the query is called the ' result set '--rownum a sequence produced in a pseudo-column ' result set ', preceded by a result set, followed

1.WITH ROLLUP: Statistical data is performed on a group basis.Example: First grouping on the name field and then counting on a group basisMysql>SELECT Name,SUM(Singin) AsSingin_count from Employee_tbl GROUP by name with ROLLUP;+--------+-------------

MySQL only provides the union, does not provide the difference set, and the intersection, but we can use the Union to achieve the intersection and the difference, the following is the implementation method:First create two tables:ERROR 1064

Name Kecheng Fenshu Tom Chinese 81 Tom Mathematical 75 John doe Chinese 76 John doe Mathematical 90 Harry Chinese 8

Having Having is used in a select expression to filter records that are already group by statistics. After the group by statistic record, the having will filter the records that match the conditions in the HAVING clause. The syntax is as follows:

Reprint: http://www.cnblogs.com/hellokitty1/p/4194841.html--Product Category table--CREATE TABLE Category (cat_id INT PRIMARY KEY auto_increment, #类别编号Cat_name VARCHAR (in) not null# category name);--Commodity table--CREATE TABLE Goods (goods_id INT

Https://www.2cto.com/database/201710/688377.html1, the role of triggers?A trigger is a special stored procedure that is executed primarily by triggering an event. It can enforce constraints to maintain the integrity and consistency of data, and can

a multiple-table query using the SELECT clause Select field name from Table 1, table 2 ... WHERE table 1. Fields=table 2. Fields and other query conditions select A.id,a.name,a.address,a.date,b.math,b.english,b.chinese from Tb_demo065_tel as B,tb_

1 , duplicate records in the lookup table are judged by a single field (Peopleid).SELECT * from peoplewhere Peopleid in (select Peopleid from People GROUP by Peopleid have count (Peopleid) > 1)Example Two: Select * from TestTable where numeber in

1, in the interview encountered a problem, is to write a table with ID and name two fields, query out the name duplicate all data, now listed below:SELECT * FROM Xi a WHERE (a.username) in (select Username from XI Group by username have count (*) >

In everyday SQL queries, we need to process the data that we want to query, and then query it in the pre-processed data. At this point we need to use the temporary table, pre-processing the data into the temporary table, and then in the temporary

/* 数据如下： name val memo a    2   a2(a的第二个值) a    1   a1--a的第一个值 a    3   a3:a的第三个值 b    1   b1--b的第一个值 b    3   b3:b的第三个值 b    2   b2b2b2b2 b    4   b4b4 b    5   b5b5b5b5b5 */--创建表并插入数据： create table tb(name varchar(10),val int,memo varchar(20))

DatabaseA database (DATABASE,DB) is a collection of organized, shareable data that is stored in a computer for a long period of time. The data in the database is organized, described and stored in a certain mathematical model, with small redundancy,

This article contains the following content:1. Oracle PL/SQL usage2.5 Constraints in Oracle (non-NULL constraints, UNIQUE constraints, PRIMARY KEY constraints, FOREIGN KEY constraints, check constraints)3, Oracle single quotation mark, double

rowID is the data stored in the database, automatically the encoding for that data, each data has a different encoding, we can quickly determine a column based on rowID , and then manipulate it.This is the database to check the weight, and delete

The distinct (STR) function is used to remove duplicate records, but it is only possible to repeat for a certain field. For example: SELECT DISTINCT (name) from TableName; However, if you want to query the records of other field values, I started

net stop MySQLnet start MySQLMysql-uroot-p--tee=c:\log.logshow databases;Create Database dbname;Drop Database dbname;show databases;Use dbnameShow tablesFRM table structure, myd table data, myi table indexCREATE TABLE User (id int,name varchar (),