A core SQL statement, SELECT retrieves data from one or more tables or other sources of row set data such as views or table-valued functions.

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cross self join to get more rows - better solution?

I have a table employees: +----------------+------------------+ | Field | Type | +----------------+------------------+ | id | int(10) unsigned | | persons_id | ...
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750 views

T-SQL, show a set of rows (specific column) as a field, for a better desc, please see the table relationship

I have been having a problem for quite a while now, that I can show with a sample of 5 tables (I'm actually dealing with more than 5!): -------------------------------- shipments ...
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62 views

Oracle: guaranteeing unmodified database state with queries?

If the first word of a SQL statement is either WITH or SELECT, is the statement guaranteed not to change the state of the database? i.e. is this loop "safe"? read SQL string if string begins with ...
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707 views

How to improve the performance of this select query?

I have two tables: TABLE1 and TABLE2. And I am running this select query to fetch the data. It takes long time to run: SELECT TABLE1.* , TABLE2.COL1 , TABLE2.COL4 FROM TABLE1, TABLE2 WHERE ...
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Select next and previous rows

I have the following table: CREATE TABLE post ( id bigint primary key, thread_id bigint, is_notice boolean, title text, content text ) I display the list ...
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55 views

Altering strings while selecting them

I'm working in SQL Server 2008, I have a varchar(255) column in my table, I want to select out all of the strings which contain the ':' character, and select the first part of the string before (but ...
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8k views

Delete from table where multiple fields match select subquery from other table

I want to delete an entry in a table where multiple fields match the results of another select subquery which takes data from another table. This is what I have so far, though it doesn't work: ...
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2answers
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Order by on an alphanumerical column

I have a column that has strings of the following type: Miller 10 Allen 20 King 10 .... Jones 100 I try to sort the column based on the numerical part of the data. I tried the following: SELECT ...
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Need a way to query a table, and JOIN it with the TOP 1 related record from an other table

As a follow up to this question, I'm wondering if there is a better and/or more efficient way to gather the data in question. As stated, this query does return me 95% of the data I need -- SELECT ...
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Getting repeated value in a group_concat only if ids are different

I have two tables, first the table Product: id|category_id --+----------- 1 | 12345 2 | 12345 3 | 12465 And then a table activity: id|prod_id|activity_type |description ...
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How to COUNT number of rows with LIMIT?

I want to catch X rows, thus, I set LIMIT X; but how can I simultaneously count the total number of rows too? Currently, I use two separate queries to do so as SELECT COUNT(*) FROM col WHERE CLAUSE ...
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Why this query returns rows that I don't want to be there

I'm trying to running this query: SELECT * FROM (`default_users`) LEFT JOIN `default_profiles` ON `default_profiles`.`user_id` = `default_users`.`id` WHERE `default_users`.`group_id` ...
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Multiple left join where not in another table

I have the following tables (there is more detailed data in each one, I just put the minimum to create a sample): __________ _____________ _____________ _____________ | person | | provider | | ...
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SELECT and UPDATE in a single query while updating selective fields of duplicate records only

I have a MySQL table named Contacts_table with, say, the following contents: ID NUMBER NAME CITY 001 2222222222 John Doe Los Angeles 002 ...
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28 views

select group by with multiple AND conditions on the same columns

I've an sql table like this: SID|SERVICE_SID|ATTRIBUTE_SID|VALUE 1 2 5 "VAL1" 2 2 4 "VAL8" 3 2 3 "VAL4" 4 11 5 ...
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1answer
40 views

Unexpected empty result [closed]

select a,b from table1 where a not in (select x as a from table2) AND b not in (select y as b from table3) The above query gives an empty result. Why? And how should I construct this combined ...
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46 views

joins with “could be blank” conditions

Question is most probably stupid but I am stuck on this and cant think anymore(Pissed Off). I have these tables-> employee(has a column foreign to location),location and location_flag. And I need ...
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1answer
846 views

Group by age range and gender with aggregation function on some columns

In Mysql, I have a patient table with id, birth_year and gender. Next table is transactions in which I have id, patient_id [FK from patient] and checkup_date. I need to select rows such that I get ...
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Multiple SELECT vs single SELECT over TCIP

My question is a performance one: I need to select roughly 400+ rows, i know their ids. currently i loop in code and fire off multiple queries over tcp/ip - because its easy: ... select [columns] ...
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`Select` query take more time than it should

I have a MySQL database table with nearly 23 million records. This table has no primary key, because nothing is unique. It has 2 columns, both are indexed. Below is its structure Below is some of ...
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169 views

How to calculate average of list of qualifications of each pupil MYSQL

I have this database and query: http://sqlfiddle.com/#!2/b4cf72/116 And I would like to add a column with the average of the exam qualifications. However, I try doing this but it tells me there are ...
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217 views

Need to optimize simple SELECT query for InnoDB table with 2million rows

I'd like to make this query the fastest possible, since it's called really often. SELECT login_events.id FROM login_events WHERE ( DATE(created_at) >= DATE(CURRENT_DATE) AND person_id = 1 ) ...
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7k views

Select records in one table but not in another, when the second table is not matching on primary key

I have two tables from which I need only the results that appear in one table (list) which do not appear in the second table (cardinal). The list table's primary key is sku, and the table has a ...
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1answer
1k views

Insert from one row to another using cases

My original table was(being used since 2005): CREATE TABLE `request` ( `msg` VARCHAR(150) NOT NULL, `id` VARCHAR(20) NOT NULL, `ctg` VARCHAR(10) NOT NULL DEFAULT 'misc', `date` ...
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236 views

MySQL SELECT query: i want show duplicated entries

Example My query is: SELECT code_CAT FROM categories WHERE id_code IN(14,14,14,14); output is: 53724 Only one row. Instead I want this output: 53724 53724 53724 53724 How can I achieve ...
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How to change the display of an empty string in mysql command line tool?

I'm maintaining a database with InnoDB tables. These tables have some columns of type (from show create table): `val0` varchar(30) default NULL, `val1` varchar(30) default NULL, etc... From the ...
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166 views

Complex mysql selection

I have the following table, id | booki_id | bet_id | bet | bettype | line | odds 1 | 123 | 321 | 1 | 3way | 0,0 | 2.3 2 | 123 | 321 | 2 | 3way | ...
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“For each group of results fullfilling condition X, select only result with smallest column value A”

I have a table with data and dates like so: DECLARE @p TABLE (P_key int, P_Data char(1), P_ValidUntil datetime) INSERT @p VALUES (20, 'T', '2003-02-28') INSERT @p VALUES (21, 'U', '2005-05-31') ...
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How to select only those records that have different/multiple for a particular field

Below is an example of my membership table. There some records having multiple values in the email field. I only want to select those records that have multiple email values: Member table ID ...
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35 views

Select data where column value exists in seperate rows for same reference id

This is on a MySQL database. Locations have services. What I want is to get all results where service_id is 2 AND 3, not OR so using IN is out I believe. Database ---------------------------- | ...
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4answers
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MSSQL Select all parent rows for which exists a combination of children rows with desired value

I would like to select all parent rows for which exists a combination of children rows with desired value. The easiest approach is to use multiple exists clauses, but this is not optimal - anyone ...
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1answer
59 views

Can I parse a text value from a specific column in a query (MySQL)?

I was playing around with Sakila and I ran across the actor_info view and one of its columns is film_info which is a detail of all the movies one actor has worked in. For example a query would be: ...
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MySQL Count rows from another table for each record in table

SELECT student.StudentID, student.`Name`, COUNT(attendance.AttendanceID) AS Total FROM student LEFT JOIN attendance ON student.StudentID = attendance.StudentID I am trying to count the last ...
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Creating a View with results from join of scalar tables

I am really bad at SQL Queries and seem to be stuck at a very odd problem. Maybe there's an alternative of doing this, but I simply can't figure it out. Maybe you guys can help! So, here's my ...
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Select only rows with minimum values from union table

SQL Server 2005 Here is a sampling of the data from a union of two tables (named "vProducts_All"): DBID UPC Price1 Price2 1 023614025559 689.0000 649.0000 2 ...
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Select statement for selecting every week's log record

Here is a simplified version of the table in question: +------------------------------------------------------+ | DatabaseName | LogRecordNumber | LogTimestamp | ...
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261 views

Determine last time a mysql table was accessed (i.e. SELECT'ed)

In my mysql DB schema there are old tables that are no longer used. I want to come up with a systematic way to show my developer a list of tables and last time they were read (SELECT'ed, not ...
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1answer
41 views

Should I drop this column or is there a query that can achieve a results table without duplicate columns?

I use a column named active in several of my database tables to adjust whether a particular entry/row/user/etc should be included in future query result tables instead of deleting the information. ...
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250 views

Running queries directly on DB2 databases

Just have a general query, if it is really fine or safe to run long select queries on RDBMS production Databases specifically DB2? If NO, what are the major risks and issues in executing select ...
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958 views

How do I query for leaf nodes in a hierarchy using a closure table?

I have some hierarchical data (representing musical instruments and playing techniques), where each leaf in the hierarchy is an audio file. The nesting depth of leaf nodes will vary because some ...
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362 views

Slow running query with inner SELECT in where clause

I have a query that looks like the following: USE DATABASE3; GO SELECT t1.COL1 AS COLUMN1, t2.COL2 AS COLUMN2, t1.COL3, t1.COL4 AS COLUMN4, t1.COL5 AS COLUMN5, ...
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312 views

INSERT INTO selected columns creates new column from JOIN [closed]

I have an INSERT INTO ... SELECT.. query that uses a JOIN on two tables. The results of the query should take a subset of the information and insert it into an existing table. That part works, but the ...
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1answer
7k views

Selecting multiple columns from multiple rows in one column (subquery?)

I'm working with MySQL 5.1.68. I have a situation where I'd like to select rows from another table into a column. I'd like to output this: id # name # citizen_name (multiple citizen names) 1 # ...
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How to run a SELECT query within while loop in PHP?

Within a SELECT query via PHP while loop, I need to run a mysql SELECT query as $result1 = $mysqli->query("SELECT * FROM table1"); while ( $row = $result->fetch_assoc() ) { if ( $row['X'] == ...
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424 views

Select records that do not have associations outside a certain list

I have a mySQL table of nodes and each node can be associated with many categories. I have a list of category ids that are acceptable (498, 499). I want to select only nodes who do not have ...
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1answer
219 views

I would like to query a range of criteria on multiple columns in MySQL

I have 3 columns in a mysql table. I'm using Innodb engine. I want to be able to search for some values on those columns and also anything close to those values. For example : We have 3 columns as ...
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357 views

How to re-arrange rows to best fit within groups?

I categorized a table with the method introduced here to categorize my items to folders with a limit size of 100. mixing_order id num_items cat order_in_cat cumulative_sum folder 1 ...
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2k views

How do I perform a UNION query on a dynamic list of tables?

My database has an unknown amount of tables, named with the same prefix followed by a random string: _ct_<random_string>. Each of these tables has the same data structure. I also have another ...
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How can I query to do this?

I have 2 tables, in feeds I have my feeds and (feeds.ID) is the primary key. second table is items. and feeds.ID is realted to items.feed_ID, so with a simple inner join i can extract the data of each ...
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286 views

Shift db data to another column

I have the following table id | ev_id | ev_loc_id | a | b | prev_a | prev_b If I the (ev_id AND ev_loc_id) not exist in the table then I just insert them, otherwise I'm putting ...