how to sql query

In the previous article "Supplement to SQL query optimization -- (in)", we mainly discussed the query statements such as select... from... where... in. Next, let's discuss Select... from... where... exists. The query speed of exists is much higher

。。。 And then you have to ask for help. I have a problem with my code about how to use arrays as SQL query statements in PHP There are currently two tables: MHF (meaning models_has_features), MHR (meaning models_has_replacements). One of the MSF

Ask the SQL Query 2 table questions: A table is ID Title Picid Where Picid storage information is A:4:{s:6: "Attach"; S:2: "S:9", "Show_type", s:1: "0"; S:9: "User_bind"; s:1: "1"; s:10: "Topic_bind"; s:0: "";} Table B is p_id purl I first

How does PHP query an SQL query that matches the value of a string and an array field? if it directly queries the records of pt $ rpt, this is the case for $ SQL & quot; SELECT * FROMuserwherept {$ rpt} & quot; now the pt field is an array. for

How does PHP query an SQL query that matches the value of a string and an array field? if it directly queries the records of pt $ rpt, this is the case for $ SQL & quot; SELECT * FROMuserwherept {$ rpt} & quot; now the pt field is an array. for

SELECT *, group_concat (, concat_ws (X, 'sku ', 'quantity-purchased'),), group_concat (, 'Order _ id ',) FROM 'Sale _ orders 'WHERE 'shipment' 0 SQL query sorting problem SELECT *, group_concat ('', concat_ws ('X', 'sku ', 'quantity-purchased'),''),

What does this SQL query statement mean? See the code today! Please look at the prawns! $sql = "Select lid, title, Htmlfile, add_time from zixun_list WHERE tid= ' $tid ' and lid <> ' $lid ' and keyword like '% '. Preg_replace ("/(, |,)/", "% ' OR

SQL query the total number of records in a table is there any faster than this? Currently it is Echo mysql_result (mysql_query ("SELECT count (table ID) from table where table Name= ' Zhang San '", $conn), 0); I'm not really happy with the

Find a SQL query statement Table Name: Archives Field: Writer pubdate Data format: 31,384,858,337 Writer= Author name Pubdate= Submission Time I need to list all the data that the author submitted for Zhang San that day, and ask for SQL query

Dede SQL query about custom properties Self added a custom attribute flag inside adds a W $sql = "SELECT * from ps_archives a,ps_addonarticle b where a.channel= ' 1 ' and A.id=b.aid and A.typeid in (SELECT ID from ps_a Rctype where Topid in (1,22,2

Oracle optimizer and SQL query execution sequence before Oracle executes an SQL statement, it first needs to check the SQL Execution Plan and then execute the SQL statement according to the execution plan, the optimizer executes the analysis of

Analyze the 48 causes of slow SQL query. There are many reasons for slow query speed. The following are common causes: 1. No index or no index is used (this is the most common problem of slow queryProgramDesign defects) 2. Low I/O throughput,

Slow SQL query speedThere are many reasons for slow query speed in SQL Server databases. The following are common causes: 1. No index or no index is used (this is the most common problem of slow query and is a defect in programming) 2. Low I/O

Three common causes of poor SQL query statement performance and Optimization Methods 1. Reasons for affecting SQL Performance There are many factors that affect SQL performance, such as incorrect initialization parameter settings and inaccurate

The SQL query always times out and expires. In WIN8, the system prompts: OLE DB or ODBC error: Query timeout has expired; HYT00 1. SQL database timeout due to database design issues:Microsoft ole db Provider for SQL Server Error '80040e31' ([odbc

Query the database select * From master. dbo. sysdatabases where name = 'database name' and status <> 512 -- read all table names in the database (current database) Select name from sysobjects where xtype = 'U' -- Read all column names of a

Basic SQL query language tutorial (3) 4. create table statementThe syntax of the create table statement is:Create Table (field1 type [(size)] [not null] [index1][, Field2 type [(size)] [not null] [index2] [,...][, Constraint multifieldindex

SQL query case: convert a column to a row using UNION ALL. After the conversion of rows and columns, you may encounter the need to replace columns.   Create table TestColRow (Name VARCHAR (10 ),East INT,South INT,West INT,North INT);   Insert into

1. Simple Query A simple Transact-SQL query only includes the select list, from clause, and where clause. They respectively describe the queried columns and the queried Tables or views, and search conditions. For example, the following statement

IDN (keyword), product name, product quantity...Table B, with fields: IDN, a_idn (record the keywords of table A), process, work hours...Table A has a one-to-many relationship with table B,I want to get the details of table A and the total work