learning sql o reilly

Tags: and fast speaking tuning market buffer way a completely"High-performance SQL Tuning essentials and Case Resolution" a book has been launched, many enthusiastic readers on the contents of the book and some of the specific questions raised questions, because of the numerous readers plus my daily work busy, here on the SQL tuning learning to discuss and a unif

Oracle learning notes 3 SQL commands, oracle learning notes SQLSQL introduction SQL supports the following types of commands: 1. data Definition Language (DDL) 2. data manipulation language (DML) 3. transaction Control Language (TCL) 4. the Data Control Language (DCL) is a detailed note of the four

Oracle learning notes 4 SQL commands (2): SQL operation language category, oracle learning notes SQL is classified into the following language categories1. Data Definition Language (DDL)Create, Alter, Drop 2. Data manipulation language (DML)Insert, Select, Delete, Update 3.

Why does the SQL Server DBA learn PowerShell? From: http://www.simple-talk.com/ SQL /database-administration/why-this-sql-server-dba-is-learning-powershell/ Joe. TJ is used only for the purpose of disseminating information. I started learning PowerShell because I was looking

, until the average score of more than 85 points. Please write a T-SQL statement implementation. 90 +: no extra points 80-89 points: Add 1 points 70-79 points: Add 2 points 60-69 points: Add 3 points 60 points below: plus 5 points 1SELECT * FROM Stumarks--Original Results2DECLARE @labAvgint--declaring variables, the user temporarily holds average points3 while(1=1)--conditions have been established4 begin5 Update Stumarks6Set labexam= Case 7When labe

) Results: As you can see from the results, Len returns the number of characters in the string. (4) Datalength, returns the actual length of the string, including spaces. 1 declare @t char (ten); 2 set @t= ' Hello '; 3 print @t; 4 Print datalength (@t); 5 Set @t=isnull (@t, ') + ' world '; 6 Print @t 7 print datalength (@t) (5) Charindex find out where a matching character appears in the string. 1 2 Select Productname,charindex (", ProductName) as N ' appears space position ' 3 fr

= Regex.match (inputstring). Value;117 MatchCollection matches = regex.matches (inputstring);118 for (int i = 0; i 119 inputstring = Inputstring.replace (Matches[i]. Value, "[" + matches[i]. Value + "]");120121}122}123 catch124 {Return "";126}127 return inputstring;128129}130131/**////132///The "[sensitive word]", converted back to "sensitive word "133 //134 //135 //136 public String Mydecodeoutputstring (string outputstring)137 {138//The sensitive word to be replaced139 String sqlstr = @ "and|

REF cursor, except that it is opened differentlyOPEN REF CURSOR name for ' SQL statement string '[using〈 parameter column];Example----Dynamic SQL-------------------------------DECLAREV_ID Number: = vid;V_name VARCHAR2 (): = ' vname ';V_sex VARCHAR2 (): = ' sex ';Insert_sql VARCHAR2 (+): = ' INSERT into student values (: 1,:2,:3) '; ---: 1 is a bound variable and is a placeholder in dynamic SQLBEGINEXECUTE

PL/SQL personal learning notes (2) and plsql personal learning notes IF condition DeclareCursor s is Select version from city_server t; S _ city_server.version % type; Begin Open s; Fetch s into s _; If s _> 2 Then DBMS_OUTPUT.put_line (s _); End if; Close s; End; LOOP Declare Cursor s is Select version from city_server t; S _ city_server.version % type;

: We'll look at the only conditions later. According to the relevant conditions and requirements to check. Get the results you want9, the company database design thinking, because of the confidentiality of the relationship, so very much detail can not describe the narrative, but when we design the table, the relationship between the foreign key and the table and table relations must be clear. Sketch assist concept when necessary.Others, and then gradually summed up the problems encountered. "

tablespace: Delete table space drop TABLE: Delete tables Drop View: Delete views Drop INDEX: Delete indexes 2.DML DML (data manipulation, Language) is used to manipulate data in a database, including some SQL statements such as the following 1) Select: Querying data in the database 2) Insert: Insert data into the database 3) Update: Updates the data in the database 4) Delete: Delete data from the database 3.DCL The DCL (Data Control Language) is used

activityPackage Com.example.freedomsql;import Com.example.freedomsql.db.dao.persondao;import Android.app.Activity;import Android.app.actionbar;import Android.app.fragment;import Android.os.bundle;import Android.view.LayoutInflater; Import Android.view.menu;import android.view.menuitem;import android.view.view;import android.view.ViewGroup; Import Android.os.build;public class Mainactivity extends Activity {@Overrideprotected void OnCreate (Bundle Savedinstancestate) {super.oncreate (savedinstan

How to Learn: Oracle SQL learning path (4): Analyzing function statistics (2) Preface I have written several blog posts about analysis functions. However, I have always been not satisfied with what I wrote, and I cannot tell where the problem is. The biggest problem is that I am not satisfied, but completely confused, and where I am not satisfied, what should I say clearly? Or the content is too thin. MAX a

number =A. Employee number)Note: this should be done to find out the maximum value of each employee's order amount, along with the information of the employee's corresponding order.Many people do this:SELECT * from order form where amount in (select Max (amount) from order Form group by employee number)This practice is wrong.3.6 quantifier QueryCommonly used quantifiers any, all, and some, where any and some are synonyms, as long as the subquery has a true, true, and all of the behavior in the

how the actual table is queried. Here is an example: SQLite>* from company_view; This will produce the following results: ID NAME Age---------- ---------- ---------- 1 Paul 32 2 allen 25 3teddy 23 4 mark 255 david 27 6 kim22 7 james 24 Delete a viewTo delete a view, simply use the DROP view statement with view_name . The basic syntax for DROP VIEW is as follows: SQLite> DROP VIEW view_name; The following command will delete the Company_view view that we created earlier: S

Simple SQL statements for database learning and Database SQL statements 1. Database Structure 1.1 Database Different databases are called Catalog (Database in some DBMS ). After using multiple Catalog, you can bring usTo the following benefits:It facilitates personalized management of each Catalog. DBMS allows us to specify whether to save different CatalogOn the

Last time we introduced:SQL/PLUS Study NotesSQL Buffer, this time we will mainly introduce the content of SQL/PLUS learning notesAutomatic SQL submissionNext, let's take a look at this part. Automatic SQL submission The automatic SQL submission function is disabled by defaul

Tags: Oracle computer language database connection SQL language probableHttp://www.w3school.com.cn/sql/index.aspSelf-study is a bumpy and need to persist in SQL. Don't know how to do it if you encounter problems! I did not know how to find the error. Here is the process of learning

SQL is a standard language for storing, manipulating and retrieving data in Databasee.Relational database: RDBMS (relational database mangement System)SQLite3 :The Rails default lightweight database, integrated in rails, is db/development.sqlite3 in this file.Use: Single use. So when the actual deployment will be replaced by MySQL and other database server.Mysql:The current popular open source database. This is a database server, to connect it require

The ninth day of SQL Learning -- SQL over In the past, we always thought that over is used in combination with row_number (). Today we suddenly found that over can also be used with Count. Now let's take a look at how it works with over! Or understand it from the example: Table creation ([DBO]. [orders] field Description: orderid -- order ID, customerid -- consum