Join Tables
Here is the breakdown of my logic on joining the tables (Please critique):
1) PC's can have many software titles and software titles can belong to many PC's but the PC can have only one copy of a particular software title.
2) Software titles can have many licenses but a license can belong to only one Software title.
3) A license to a particular software title can belong to only one PC.
The table layout I created, only relevant parts (Again, please critique):
1) tblPC has an autoincrement primary key, tblPcID.
2) tblSoftware has an autoincrement primary key, tblSoftwareID.
3) tblLicense has an autoincrement primary key, tblLicenseID. It also has a foriegn key, tblSoftwareID to tblSoftware.tblSoftwareID.
4) tbljnPcSoftware has a unique index that includes tblPcID and tblSoftwareID. tblSoftwareID is also separetly indexed. tblPcID is a FK to tblPcID.tblPcID and tblSoftwareID is a FK to tblSoftware.tblSoftwareID. I also have tblLicenseID as an index in this table.
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I am trying to write a query where a user will enter the deal id, and based on the product type of that deal id, the query will return fields specific to that product. Each product has its own table. Can I do a case statement that joins different tables based on the product of the deal number?
DISTINCT With Multiple Tables And INNER JOIN ?
My query works OK this way, but I need every "kohde_name" only once (preferred the earliest "hav_date"). I've tried with "DISTINCT kohde_name" in many ways, but always end up with syntax error...:( Is there any solution with DISTINCT, or do I need anotjer solution? my (simplified) query: SELECT henk_name,henk_number, kohde_name ,kohde_txt,havainto_id,hav_kohdetxt, hav_date FROM ((henkilo INNER JOIN havaitsija ON hja_henkilo_id=henkilo_id) INNER JOIN havainto ON hja_havainto_id=havainto_id) INNER JOIN kohde ON hav_kohde_id=kohde_id WHERE ...
Non-trivial Join Of 3 Tables, With Restrictions
given: - a league consists of several teams; table leagues has a unique league_id and all its teams have 1 foreign key, league_id, referencing their containing league. - a team consists of many players and no player can be on more than one team in the same league; to allow for variable size teams, an entry in table lineups represents one player's presence on a team. so table lineups has 2 foreign keys, team_id and player_id. - table players contains a list of all available players. want: - to be able to select all players that are not on a team in a given league. note that league_id is in table teams, all available players (for any one league) are in table players, and the players on a particular team are in table lineups. So the relevent data is scattered across 3 tables. for example: - league sample_league has 3 teams: jets, browns and falcons. - the list of all available players is jon, bob, frank, pat. - jets has jon on its team, signified by an entry in lineups with team_id=jets and player_id=jon. similarly, browns has bob on its team, and falcons has frank on its team. - there could be other entries in lineups from other leagues, like an entry for team patriots from a league called some_other_league which has player pat on their team, and another entry for team bengals from a league called yet_another_league which has bob on it. - i want to be able (in mysql 4.0.18 so no nested queries) to be able to select all the players NOT on a team in league sample_league in one statement. (in this example it should return just one player, pat).
Slow Join On Large Tables
I have two tables: D (500,000 recs), and DL (2,500,000 recs) D has a PK and an index on HLQ. DL has a PK and an index on ID. The following SQL: SELECT HLQ as "HLQ", count(*) FROM D, DL WHERE D.DLID=DL.ID GROUP BY HLQ produces the following explain: tabletypepossible_keyskeykey_lenrefrowsExtra DALL500000Using where; Using temporary; Using filesort DLeq_refIDID4D.DLID1Using index The query takes ~ 3:30 on a Athlon xp2200; 1GB RAM; default bufer settings. Adding the following buffer settings only slightly decrerased the time (~3:00). key_buffer=512M table_cache=256 sort_buffer=16M read_buffer_size=16M It appeasrs that the 'Using filesort' on table D is due to the Group By clause and is the problem. I have an index on HLQ. Is there any way to get MySQL to use it?
Join Tables On A Large Database 200 Meg
i am trying to work out the most efficient way to list say multipl= e categories of entries, the database is quite large about 200 meg.=20 I would like to know if using join tables is more efficient than storing th= e keys in a varchar field then within the second loop doing a where in (1,2= ,3,4) where the 1,2,3,4 are the stored category keys in the varchar field = rather than a where in (1), where 1 is the pirmaryID of the entry for insta= nce ?
Join 2 Tables And Limit Records From One
i've got 2 tables: Gallery Gallery_Id,Gallery_Name Images Images_Id,Gallery_Id,Images_Filename,Images_Width,Images_Height I'd like to select all galeries from Gallery and join Images to each gallery but i'd like to limit 3 images per gallery this code list all images from all galleries, i suppose that i must try with subqueries, am i wrong ? SELECT a.Gallery_Id,a.Gallery_Name,b.Images_Id,b.Images_Filename FROM Gallery AS a INNER JOIN Images AS b ON b.Gallery_Id=a.Gallery_Id
Join 2 Tables In SUM IF Statement-mysql
I am trying to join 2 tables with in a SUM IF statement. the code is as under: SELECT prod_code, description, description1, quant, SUM(IF(newsales.location = '05-P', newsales.quant,''))P, SUM(IF(newsales.location = '10-L', newsales.quant,'')) L, SUM(IF(newsales.location = '12-M', newsales.quant,'')) M, SUM(IF(newsales.location = '11-BI', newsales.quant,'')) Bi, SUM(IF(newsales.location = '14-BR', newsales.quant,'')) Br from newsales, stock where newsales.prod_code = stock.prod group by prod_code But it gives an incorrect output, but if I romove the join statement, it gives accurate resuly. How to join the 2 tables ie newsles and stock so that the output remains right.
SELECT From Two Tables + LEFT JOIN
Since MySQL v5 was released our script stoped working due to mysql query errors. i.e: SELECT a.id FROM table1 a, table2 b LEFT JOIN table3 c ON (c.id = a.id) This will return error: Unknown column 'a.id' in 'on clause' To solve this we can do in two ways: 1) change tables order in FROM statement: SELECT a.id, b.id, c.id FROM table1 b, table2 a LEFT JOIN table3 c ON (c.id = a.id) Or 2) use brackets in FROM statement: SELECT a.id, b.id, c.id FROM (table1 a, table2 b) LEFT JOIN table3 c ON (c.id = a.id) Both ways works, but I have question to the experts: which way is the most optimized/better?
Join 3 Tables - Distinct Results
I've got a database that keeps track of sales of widgets. Each company that belongs to my organiztion is to report their widget sales or no sales every month. There are several different types of widgets. Not all companies sell or report all types of widgets. We want to report how many companies have reported or not reported their sales (ie. x companies of a possible y companies have reported sales this month - y will always be the same - lets say 5). Because of the way that sales are input, "big widgets" are reported in 2 different tables called widgets_a and widgets_b. If they don't have any sales to report, they still report and it goes into a table called no_reports. Each table has a couple of common fields - ManufacturerID and OrderDate. I can search all of the tables individually to find if a manufacturer has reported - SELECT DISTINCT ManufacturerID FROM widgets_a WHERE OrderDate >= '2003-06-01' AND OrderDate <= '2003-06-30'; but I want to search through the 3 tables and find how many distinct manufacturers have reported in the given month.
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