easy sql query builder

The data architecture is the biggest headache for website development. Local Development is easy. ProgramYou only need to package the DLL, but the database needs to be transferred to the space server. accidentally, you will forget some stored procedures, triggers, and constraints. here we will provide you with several query checks. it can quickly find out what is missing. very practical. there are good met

1. Problem Introduction The main purpose is to query the data that appears in one table and not in the other, specifically: As shown, there is a, b two tables, where the aid field of Table B refers to the primary key ID of Table A, in order to query in a table appears, but not by the data referenced by B table; Qualification: The is_deleted field in A and B is ' n ' and the type in B is ' c

Sometimes you need to track your ownProgramWhich SQL query statements have been executed? In ms SQL, a dedicated tool is provided to perform this operation. MySQL does not seem to have, but it is very easy to implement this function. Find the MySQL configuration file[Mysqld]AddLog = filenameYou can.For example: Code

and s.course where s.score>=80 and s1.score>=80 and s2.score>=80) D group by D.name 　　Easy wrong point: the score field of the inner table must be alias, otherwise it will error. Method Two: 　　Thinking : using reverse thinking to think about ... To find that the results are more than 80 of the people, but also to find out that there is a score of less than 80 people, and then remove these people are not more than the number of people are

worker Set name = ' Transaction modification ' where employee number = ' Zg2 'ROLLBACK TRANSACTION Update_data9.3 Save TransactionSyntax format:Save{tran | transaction} {savepoint | @savepoint_variable}Note: When a transaction begins, the resources used during transaction processing are persisted until the transaction completes (that is, locked). When a part of a transaction is rolled back to the savepoint, the resource continues to be retained until the transaction completes (or the entire tra

due to planned regression. If you find a plan to return, it's easy to force a specific schedule without using the Schedule wizard. Sounds interesting? Let's take a specific scenario and show you how to use query storage in SQL Server 2016 to find and eventually revise the regression of the plan. Query store--my oppon

buffer cache, the corresponding page read will be discarded when the read is complete. If the page already exists in the cache, you can also "crop" the extent of the page from either end.So, if our tables are not physically contiguous pages, then the number of reads is not good how to determine.Let's look at an example of a heap table.SET STATISTICS IOon--** from Neworders_testThe number of pre-reading here is 8 times, so I estimate that the underlying data page is definitely not sequential. So

A common method to improve the efficiency of SQL query(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table (the underlying table, driving tables) will be processed first, and in the case where the FROM clause contains more than one tabl

"SQL performance optimization is a black magicJust like alchemy:Various formulations are difficult to understand and obscure,Only a small number of people in the circle can understand. ” This is a misconception that SQL database uses a known algorithm to implement performance that can be expected. The problem, however, is that it is easy to write

connected Seven query string data using variablesSelect*fromtb_namewherenamelike '%$_post[name]% 'A fully matched method of "percent%" means that it can appear in any location Eight queries before N recordsSelect*fromtb_namelimit0, $N;Limit statements are used in conjunction with other statements, such as an order by, and can be used in a variety of SQL statements, making the program very flexible Nine

number of records is n then the time to make a connection query is the complexity of O (m*n). A visible connection query is time consuming, and if the table has a very large number of records, the query efficiency becomes very low. So in the writing of SQL statements, especially complex connection

First, the question: The database is Ms SQLServer2000, to the SQLServer2000 of a table of data into the MySQL5, where SQLServer2000 table fields in Simplified Chinese name (strongly recommended not to do in Chinese as field name). In fact, the operation is to SQL Server query records, inserted into MySQL. The selected scripting language is php,php open MSSQL and MySQL extensions, which are

Label:I've often been asked this question repeatedly: "I have a poorly performing SQL Server." How do I find the worst performance query? “。 So in today's article there are some information and wizards that make it easy to find answers to your questions.Ask SQL server!One advantage of

an index.6. Accelerating queries with temporal tablesSorting a subset of tables and creating temporary tables can sometimes speed up queries. It helps to avoid multiple sorting operations, and in other ways simplifies the work of the optimizer. For example:SELECT cust.name，rcvbles.balance，……other COLUMNS FROM cust，rcvbles WHERE cust.customer_id = rcvlbes.customer_id AND rcvblls.balance>0 AND cust.postcode>“98000” ORDER BY cust.nameIf the query is to

At present, the application of network database has become one of the most widely used, and the security of database, performance is the most important thing that enterprises care about. The database is becoming the lifeblood of the enterprise, and optimizing the query solves every performance issue with regard to database applications, and here's what Microsoft SQL Server has done for us.Optimization

IntroductionViews can be thought of as virtual tables that are defined on SQL Server. The view, as its name implies, is another entry for viewing data. The general view itself does not store the actual data, but only a SELECT statement and the metadata of the table involved.The view is simple to understand as follows:With views, clients no longer need to know the table structure of the underlying table and the relationships between them. The view prov

Label:　　 Phoenix is a good hbase query tool, which is also easy to install in HBase, and can be configured as a client and server Phoenix in the http://www.cnblogs.com/laov/p/4137136.html connection. Phoenixsql has the following classes: Delete data: Executableaddcolumnstatement, Executabledropcolumnstatement Create/delete table: Executablecreatetablestatement, Executabledroptablestatement

Scenario 5 Using XML parametersChildren's shoes unfamiliar with SQL Server XML type parameters need to understand the concept of XQuery first, where XQuery is a language used to find and extract elements and attributes from XML documents, simply the language used to query XML. That would lead to XPath, In fact, XPath is a subset of XQuery, and XQuery 1.0 and XPath 2.0 share the same data model and support t

bother about which data table The 13 records study is placed on. Of course, when querying data, you can also ignore the fact that the data is stored in the Physical data table. Query using the following SQL statement:[C-sharp]View Plaincopy SELECT * FROM Sale The results of the query are as follows:From the above two steps, it is not felt that the

(BUSINESSSTATUS1,BUSINESSSTATUS2)The following query is to query the so-called special dataSELECT * from businesstable where businessstatus1=3 and businessstatus2=10Find the execution plan as follows: The whole table scan, the IO cost is not small,In this case, obviously there is only one data, but to go full-table scan(There is not only one such coincidence in the actual business, but in the Tens table, t