sql in 10 minutes

omitted this step.7. The law of the WHERE statement7.1 Avoid using in,not in,or or having in the WHERE clause.You can use exist and not exist instead of in and not.You can use table links instead of exist. Having can be replaced by where, if not replaced, can be handled in two steps.Example (SELECT customer_name from CUSTOMER) Optimization (SELECT customer_name from CUSTOMER) 7.2 Do not declare numbers in character format, you want to declar

relationship to this new employee object and the new Territory object. Call SubmitChanges to persist these new objects and their relationships to the database.4. Using dynamic CUD overrides (override using dynamically CUD)Description: CUD is the abbreviation for Create, Update, delete. The following example is to create a new ID (primary key) of region 32, regardless of the database has no ID 32 data, if any, replace the original data, not inserted.New Region () { , "Rainy"};d B. Regions.

seconds (1/(24*60*60)), if not required so accurate, can be omitted this step.7. The law of the WHERE statement7.1 Avoid using in,not in,or or having in the WHERE clause.You can use exist and not exist instead of in and not.You can use table links instead of exist. Having can be replaced by where, if not replaced, can be handled in two steps.Example (SELECT customer_name from CUSTOMER) Optimization (SELECT customer_name from CUSTOMER) 7.2 Do

define a variable, what happens when you compare it with a variable? First we create a filter index CREATE nonclustered INDEX idx_salesorderdetail_productid On Sales.SalesOrderDetail (ProductID) 870 Using variables to compare with query criteria, forcing the use of filtered indexes (clustered index by default) Use AdventureWorks2012 GO DECLARE @ProductID INT 870 SELECT ProductID from Sales.SalesOrderDetail with (INDEX ([Idx_salesorderdetail_productid])) = @ProductID Looking at the query

Oracle version: 10.2.0.1 OS: Linux 64-bit Regular expressions are used in SQL: Select count (*) From t Where regexp_like (T. Note, '^ (. | +) * (\ (either \) +', 'I ') The first execution can be performed, the second execution reports ORA-7445, session interruption. The records in the trace file are as follows: Exception signal: 11 (SIGSEGV), Code: 1 (address not mapped to object), ADDR: 0x5e, PC: [0x2a95574358, _ intel_fast_memcpy.a () +

CREATE Table #timeseries (times datetime NOT NULL)GoDECLARE @firstdate datetime, @lastdate datetimeDECLARE @MI intBeginSet @firstdate = ' 8/8/2012 6:00 'Set @lastdate = ' 8/9/2012 6:00 'Set @MI =datediff (MI, @firstdate, @lastdate)--Nested Loopswhile (@MI >=0)BeginINSERT INTO #timeseriesVALUES (@firstdate)SET NOCOUNT onSet @firstdate =dateadd (mi,10, @firstdate)-increments by 10 minutes per start time.Set @

Oracle Performance Analysis 10: Re-indexing-common SQL The previous section describes the causes and methods for re-indexing. This section describes several common SQL statements and stored procedures.Query all invalid global indexes select index_name, status from user_indexes where table_name = upper(table_name) and status = 'UNUSABLE'Query all invalid partit

Step by step vs 2008 +. Net 3.5 (10)-add, query, update, and delete a stored procedure call using dlinq to SQL Author: webabcd IntroductionTaking northwind as the example database, dlinq (LINQ to SQL) calls the ADD, query, update, and delete operations of a specified stored procedure. ExampleRelated stored proceduresAlter procedure [DBO]. [spinsertcategory] @ Cat

Tags: seed. com init S3 thread library rar processing VDIPerformance considerations for an availability group that creates an automatic seed settingSQL Server uses a fixed number of threads for automatic seeding. In the primary instance, SQL Server uses one thread for each LUN to read the changes. In a secondary instance, SQL Server uses a thread for each LUN to initialize the database.During automatic seed

omitted this step.7. The law of the WHERE statement7.1 Avoid using in,not in,or or having in the WHERE clause.You can use exist and not exist instead of in and not.You can use table links instead of exist. Having can be replaced by where, if not replaced, can be handled in two steps.Example (SELECT customer_name from CUSTOMER) Optimization (SELECT customer_name from CUSTOMER) 7.2 Do not declare numbers in character format, you want to declar

from user_indexes WHERE table_name = UPPER (v_table_name) and partitioned = ' YES ') LOOP for I_parti Tion_name in (SELECT partition_name from User_tab_partitions WH ERE table_name = UPPER (V_table_name)) LOOP SELECT status into V_status from User_ind_partitions W Here index_name = i_index_name.index_name and partition_name = I_partition_name.partition_name; If V_status = ' unusable ' then Dbms_output.put_line (I_partition_name.partition_name | | ' : ' || I_inde

column brand_code intable brand ) brand_name =All lines of the ' BMW 5 series ' ). The code above is stitched together by two lines of code below. Select Brand _code from brand where brand_name = ' BMW 5 series ' Look for the brand_name in the column brand_code in table brand =' BMW 5 Series ' of all lines Select *from car where brand= ' b004 ' Find All rows of column brand=' b004 ' in table car ---------- foreign KEY constraints ALTER TABLE foreign key table name add constraint const

2014-10-13 16:44:28goal : replace integers with decimalsanti-pattern : Using float typeAccording to the IEEE754 identity, the float type encodes real data in binary format.Cons: (1) The necessity of rounding: not all of the information described in the decimal can be stored using binary, in some necessary factors,A floating-point number is usually rounded to a very close value.Example: Select rate from A where id=123--result:59.95SELECT * from A where

statement. Because these two operations will lock the table, the table is locked, and other operations are not in, as far as I would rather I would like to use a for loop to perform each of these operations. 6. Never easily use ORDER by rand (), which is likely to lead to MySQL disaster 7, each table should be set an ID primary key, the best is an int type, and set on the automatic addition of the AUTO_INCREMENT flag, which should actually be used as the first thing in the design table structur

In and Existsin is the appearance and the inner table as a hash connection, and exists is the external loop loop, each loop loop and then query the internal table. The assertion that exists is more efficient than in is inaccurate. If the two table size of the query is equal, then the in and exists are not very different. If one of the two tables is smaller, one is a large table, then the subquery table is large with exists, and the subquery table is small in: For example: Table A (small table),

Reply content: First, attach the MySQL official documentation excerpt and Link: ORDER BY RAND()Combined with are LIMIT useful for selecting a random sample from a set of rows: Simple translation of the above (for students who are not good at English): ORDER BY RAND()And LIMIT used together, can be used to select a random part from multiple rows of results mysql> SELECT * FROM table1, table2 WHERE a=b AND c 其次，使用Laravel Eloquent的查询器（query builder），需要用到DB（Facade）进行原生

Increase1.insert InsertionSyntax:insert[into]Cases:Insert into Student (name, gender, date of birth) values (' Wang Weihua ', ' Male ', ' 1983/6/18 ')2. Inserting a tableSyntax: Insert intoExample: INSERT into AddressList (' name ', ' address ', ' email ') Select Name,address,email from studentsBy deleting1.deleteSyntax: Delete from table name where column name =[column value]Example: Delete from student where name= ' Wang Weihua '2.truncateSyntax:truncateChange1.updateSyntax:updateExample: Upda

* FROM Table ORDER by RAND () LIMIT 20; Use the following statement instead: SELECT * FROM table as T1 JOIN ( Select ROUND (RAND () * ((select MAX (ID) from table)-(select min (id) from table) + (select min (id) from table)) as ID ) as T2 WHERE t1.id >= t2.id ORDER by t1.id LIMIT 1; This is to get a random record so that even if executed 20 times, it is more efficient than the original statement. or first use PHP to generate a random number, the string is passed to Mysql,mysql in query. Princi