tricky sql queries

SQL query special data that does not include date SQL quot; select * fromtestwheredatesnotin (#2010-05-03 #, #2010-05-12 #) quot; the date format must be prefixed with # so that we can find all the data that does not include #2010-05-03 #, #2010-05-12 #. Then, let's look at the stupid method 2 SQL quot; sele SQL

--Check the database for wait eventsFrom v$session_waitWhere event is not a like ' sql% ' and an event not a like ' rdbms% '--Find time-consuming operations in the systemSelect B.username Username,a.disk_reads reads,A.executions Exec,a.disk_reads/decode (a.executions,0,1,a.executions)Rds_exec_ratio,A.sql_text statementFrom V$sqlarea A,dba_users bwhere a.parsing_user_id=b.user_idand A.disk_reads >100000ORDER BY a.disk_reads Desc;--View the time-consumi

corresponding column in the database. Improveduse ParameterDirection (Specify a query within the DataSet the type of the parameter. ) enumeration type to improve the above.Where ParameterDirection has four members: input parameter, output parameter, inoutput (input and output parameter), ReturnValue (return value of the operation)Passing parameter Proceduresintroduction of ParameterDirectionSummaryBy introducing ParameterDirection, the efficiency of the query is improved, on the other hand it i

the argument, a lot of kinky think of a variety of alternativesScenario 1, using the charindex or like method to implement parameterized queries , without a doubt, this method succeeds, and successfully reused the query plan, but also completely invalidate the query index (not discussed in the index topic), the result is a full table scan, If the amount of data in the table is large, millions, tens, or even more, such a writing will have disastrous c

virtual memory size to be at least 3 times times the physical memory installed on the computer. Configure the SQL Server max server memory server configuration option to 1.5 times times the physical memory (half of the virtual memory size setting).7. Increase the number of server CPUs, but it is important to understand that parallel processing of serial processing requires resources such as memory. The use of parallel or string travel is the MSSQL au

request is received. The query layer parses the SQL and produces an optimized execution plan by the executor, which is then referred to the execution engine to the storage layer for querying and calculation.If you need to use fireworks engine calculations, the query layer will further convert the execution plan into a distributed execution plan and submit it to the fireworks Cluster as a distributed task after the execution plan is obtained. The remo

to 32 layers. Individual queries may not support 32-tier nesting. 5. Any place where you can use an expression can use a subquery, as long as it returns a single value. 6. If a table appears only in the subquery and does not appear in the outer query, the columns of the table cannot be included in the output.Three, simple sub-queryExample: Select Name,age from -person where > (select-age-from-person WHERE name = ' Sun Quan ' ) The output is: 　

SQLServer no selectPr_Nameas [Stored Procedure], [Parameter] stuff (select, + [Parameter] from (selectPr. nameasPr_Name, parameter. name ++ Type. name + (+ convert (varchar (32), parameter. max_length) +) asParam SQL Server queries all stored procedure information, triggers, and indexes without the select Pr_Name as [Stored Procedure], [Parameter] = stuff (select ',' + [Parameter] from (select Pr. name as P

SQL Server queries all database names, table names, and field names. For more information, see. SQL Server queries all database names, table names, and field names. For more information, see. 1. Get all database names:SELECT Name FROM Master .. SysDatabases order by Name 2. Get all table names:SELECT Name FROM D

CREATE TABLE Emp(Eid char (primary key),ename char (20),Age-Integer Check (age > 0),Did char (20),Salary float,)CREATE TABLE Dept(Did char (primary key),Dname Char (20),Mgr_did Char (20),)ALTER TABLE EMP add constraint Fk_emp_did foreign key (did) references Dept (DID)ALTER TABLE Dept add constraint fk_dept_mgrdid foreign key (Mgr_did) references Emp (EID)Title: Write an SQL statement that queries the name

How can I quickly find the values in JSON by referring to the KBMMW JSON object operation?One way is through the method of traversal, in fact, in KBMMW there is a flexible way to query,is to query the values in JSON by SQL. In other words, the Tkbmmwmemsql control is used to implement.Tkbmmwmemsql can also be used to query XML and CSV files, just talk about JSON queries today.We first put a tkbmmwmemsql con

--returns a list of linked servers defined in the local server. EXECsys.sp_linkedservers/*creates or updates a mapping between logins on a local instance of SQL Server and security accounts in the remote server. When a user logs on to a local server and executes a distributed query to access a table on a linked server, the local server must log on to the linked server and access the table on behalf of that user. Use sp_addlinkedsrvlogin to specify th

1, temporary use method OpenRowsetA. Using OPENROWSET with SELECT with Microsoft OLE DB Provider for SQL ServerThe following example uses Microsoft OLE DB Provider for SQL Server to access the authors table of the pubs database on a remote data server named REMOTE1. Initializes the provider from DataSource, user_id, and password, and uses SELECT to query the data table.SELECT * from OPENROWSET (' SQLOLEDB '

Purpose: To filter the sum of two fields in a table as a where conditionQuerying for records with no expirationSelect a, from Test where a+b>now ();//A: Deposit time B: Validity period SQL will error when you make the above query.However, simply put the above SQL into the code and replace now () with the method of the current timestamp obtained by the corresponding language (e.g. time () in PHP), execute,

] . "‘,"; } } $group _account=RTrim($group _account, ‘,‘); $sql _all_account= "Select DISTINCT ' AccountName ', ' agentid ', ' ServerID ', ' Platform ', ' mTime ' from ' t_log_register ' WHERE ' AccountName ' in ( {$group _account}) and ' MTime ' $now _end_time}‘ "; $all _account= Fetchrowset ($sql _all_account); if(!Empty($all _account)){ Break; } }

parallel, said the update statistics to try first.a hit! a hit! a hit! Execute the following code:Update STATISTICS ods_table_a by default, the query optimizer updates the statistics as needed to improve the query plan, but in some cases, you can improve query performance by using update STATISTICS or stored procedure sp_updatestats to update statistics more frequently than the default updates. new inserted data no statistics, large table Automatic UPDATE STATISTICS trigger Automatic Update me

Tags: Join SQL query div class name Cat data query SEL styleA brand table A classification table foreign key for the brand's ID Search brand information corresponding to identify the brand under the category number of SQL Original sql: Select b.id, b. NAME, ( select COUNT (*) from jc_goods_cat WHERE Goods_brand _id = b.id ) catnum from Jc_goods_brand b The query

logical reads, physical reads, and read-ahead concepts are understood to be similar, but only when the corresponding table is updated or inserted.For scan count, the query with slices is not connected, so it makes little sense. However, if a connection query, especially a circular query, such as self-connection, if the number of cycles, the more the number of scans, it will make the query less efficient. This is the scan count is a more important performance embodiment parameter.In the case of

Bush George Fifth Avenue New York Example 2Next. We want the last name of the record selected from the "Persons" table to start with "C". Then there is a random character, then "R", then a random character. Then there is "ER":We are able to use the following SELECT statement:SELECT * from Personswhere LastName like ' c_r_er 'Result set: Id LastName FirstName Address City 3 Carter Thomas Changan Str

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