I'm selecting columns from one table and would like to select all values of a column from a related table when the two tables have a matching value, separate them by commas, and display them in a single column with my results from table one.
I'm fairly new to this and apologize ahead of time if I'm not wording it correctly.
It sounds like what you're trying to do is to take multiple rows and aggregate them into a single row by concatenating string values from one or more columns. Yes?
If that's the case, I can tell you that it's a more difficult problem than it seems if you want to do it using portable SQL - especially if you don't know ahead of time how many items you may get.
The Oracle-specific solution often used in such cases is to implement a custom aggregate function - STRAGG(). Here's a link to an article that describes exactly how to do so and has examples of it's usage.
If you're on Oracle 9i or later and are willing to live with using undocumented functions (that could change in the future), you can also look at the WM_CONCAT() function - which does much the same thing.
You want a row aggregation or concatenation function, choices are:
If you are using Oracle 11gR2, there is a built-in function to aggregate strings with a delimiter called LISTAGG(column, delimiter).
If you are using any earlier release of Oracle database, you can use WM_CONCAT(column) function, however you have no choice of delimiter and will have to use something like TRANSLATE(string, string_to_replace, replacement_string) function to change the delimiter afterwards if your data does not contain commas.
As mentioned by LBushkin, you can create a custom function in your schema to perform row aggregation for you. Here is PL/SQL code example for one: http://www.oracle-base.com/articles/misc/StringAggregationTechniques.php#user_defined_aggregate_function
Related
I have a PostgreSQL column of type text that contains data like shown below
(32.85563, -117.25624)(32.855470000000004, -117.25648000000001)(32.85567, -117.25710000000001)(32.85544, -117.2556)
(37.75363, -121.44142000000001)(37.75292, -121.4414)
I want to convert this into another column of type text like shown below
(-117.25624, 32.85563)(-117.25648000000001,32.855470000000004 )(-117.25710000000001,32.85567 )(-117.2556,32.85544 )
(-121.44142000000001,37.75363 )(-121.4414,37.75292 )
As you can see, the values inside the parentheses have switched around. Also note that I have shown two records here to indicate that not all fields have same number of parenthesized figures.
What I've tried
I tried extracting the column to Java and performing my operations there. But due to sheer amount of records I have, I will run out of memory. I also cannot do this method in batched due to time constraints.
What I want
A SQL query or a sequence of SQL queries that will achieve the result that I have mentioned above.
I am using PostgreSQL9.4 with PGAdmin III as the client
this is a type of problem that should not be solved by sql, but you are lucky to use Postgres.
I suggest the following steps in defining your algorithm.
First part will be turning your strings into a structured data, second will transform structured data back to string in a format that you require.
From string to data
First, you need to turn your bracketed values into an array, which can be done with string_to_array function.
Now you can turn this array into rows with unnest function, which will return a row per bracketed value.
Finally you need to slit values in each row into two fields.
From data to string
You need to group results of the first query with results wrapped in string_agg function that will combine all numbers in rows into string.
You will need to experiment with brackets to achieve exactly what you want.
PS. I am not providing query here. Once you have some code that you tried, let me know.
Assuming you also have a PK or some unique column, and possibly other columns, you can do as follows:
SELECT id, (...), string_agg(point(pt[1], pt[0])::text, '') AS col_reversed
FROM (
SELECT id, (...), unnest(string_to_array(replace(col, ')(', ');('), ';'))::point AS pt
FROM my_table) sub
GROUP BY id; -- assuming id is PK or no other columns
PostgreSQL has the point type which you can use here. First you need to make sure you can properly divide the long string into individual points (insert ';' between the parentheses), then turn that into an array of individual points in text format, unnest the array into individual rows, and finally cast those rows to the point data type:
unnest(string_to_array(replace(col, ')(', ');('), ';'))::point AS pt
You can then create a new point from the point you just created, but with the coordinates reversed, turn that into a string and aggregate into your desired output:
string_agg(point(pt[1], pt[0])::text, '') AS col_reversed
But you might also move away from the text format and make an array of point values as that will be easier and faster to work with:
array_agg(point(pt[1], pt[0])) AS pt_reversed
As I put in the question, I tried extracting the column to Java and performing my operations there. But due to sheer amount of records I have, I will run out of memory. I also cannot do this method in batched due to time constraints.
I ran out of memory here as I was putting everything in a Hashmap of
< my_primary_key,the_newly_formatted_text >. As the text was very long sometimes and due to the sheer number of records that I had, it wasnt surprising that I got an OOM.
Solution that I used:
As suggested my many folks here, this solution was better solved with a code. I wrote a small script that formatted the text as per my liking and wrote the primary key and the newly formatted text to a file in tsv format. Then I imported the tsv in a new table and updated the original table from the new one.
I have a query that is returning data from a database. In a single field there is a rather long text comment with a segment, which is clearly defined with marking tags like !markerstart! and !markerend!. I would like to have a query return with the string segment between the two markers removed (and the markers removed too).
I would normally do this client-side after I get the data back, however, the problem is that the query is an INSERT query that gets it's data from a SELECT statement. I don't want the text segment to be stored in the archival/reporting table (working with an OLTP application here), so I need to find a way to get the SELECT statement to return exactly what is to be inserted, which, in this case, means getting the SELECT statement to strip out the unwanted phrase instead of doing it in post-processing client-side.
My only thought is to use some convoluted combination of SUBSTRING, CHARINDEX, and CONCAT, but I'm hoping there is a better way, but, based on this, I don't see how. Anyone have ideas?
Sample:
This is a long string of text in some field in a database that has a segment that needs to be removed. !markerstart! This is the segment that is to be removed. It's length is unknown and variable. !markerend! The part of this field that appears after the marker should remain.
Result:
This is a long string of text in some field in a database that has a segment that needs to be removed. The part of this field that appears after the marker should remain.
SOLUTION USING STUFF:
I really don't like how verbose this is, but I can put it in a function if I really need to. It isn't ideal, but it is easier and faster than a CLR routine.
SELECT STUFF(CAST(Description AS varchar(MAX)), CHARINDEX('!markerstart!', Description), CHARINDEX('!markerend!', Description) + 11 - CHARINDEX('!markerstart!', Description), '') AS Description
FROM MyTable
You may want to consider implementing a CLR user-defined function that returns the parsed data.
The following link demonstrates how to use a CLR UDF RegEx function for pattern matching and data extraction.
http://msdn.microsoft.com/en-us/magazine/cc163473.aspx
Regards,
You can use Stuff function or Replace function and replace your unwanted symbols with ''.
STUFF('EXP',START_POS,'NUMBER_OF_CHARS','REPLACE_EXP')
Oracle has a function called translate that can be used to replace individual characters of the string by others, in the same order that they appear. It is different than the replace function, which replaces the entire second argument occurence by the entire third argument.
translate('1tech23', '123', '456'); --would return '4tech56'
translate('222tech', '2ec', '3it'); --would return '333tith'
I need this to implement a search on a SQLite database ignoring accents (brazilian portuguese language) on my query string. The data in the table that will be queried could be with or without accents, so, depending on how the user type the query string, the results would be different.
Example:
Searching for "maçã", the user could type "maca", "maça", "macã" or "maçã", and the data in the table could also be in one of the four possibilities.
Using oracle, I would only use this:
Select Name, Id
From Fruits
Where Translate(Name, 'ãç','ac') = Translate(:QueryString, 'ãç','ac')
... and these other character substitutions:
áéíóúÁÉÍÓÚàèìòùÀÈÌÒÙãõÃÕäëïöüÄËÏÖÜâêîôûÂÊÎÔÛñÑçÇ
by:
aeiouAEIOUaeiouAEIOUaoAOaeiouAEIOUaeiouAEIOUnNcC
Of course I could nest several calls to Replace, but this wouldn't be a good choice.
Thanks in advance by some help.
Open-source Oracle functions for SQLite have been written at Kansas State University. They include translate() (full UTF-8 support, by the way) and can be found here.
I don't believe there is anything in sqlite that will translate text in a single pass as you describe.
This wouldn't be difficult to implement as a user defined function however. Here is a decent starting reference.
I used replace
REPLACE(string,pattern,replacement)
https://www.sqlitetutorial.net/sqlite-replace-function/
I'm a SQL Server 2005 newb and I have to do something that should be easy but I'm having difficulties.
For the time being my stored procedure is storing csv in one column in my db. I need to break apart the csv into multiple columns. The number of values in a the CSV parameter is static, there is always gonna be 8 values and they are always going to be in the same order. Here is an example of the data:
req,3NxWZ7RYQVsC4chw3BMeIlywYqjxdF5IUX8GMUqgJlJTztcXQS,192.168.208.78,getUserInfo,AssociateService,03303925,null,M042872,
What is the best function to use to separate this parameter in a stored proc so I can then insert it into separate columns? I was looking at substring but that seems to be positional and not regex aware??
Thanks,
Chris
SQL Server doesn't have the native functionality; you have to build a function (generally referred to as "split"). This thread provides a number of TSQL options, looking for the same answer you're after--what performs best. Where they lack is in testing large amounts of comma delimited data, but then your requirement is only for eight values per column anyway...
SQL Server 2005+ supports SQLCLR, where functionality can be handed off to .NET code. The .NET code has to be deployed to the SQL Server instance as an assembly, and TSQL functions/procedures need to be created to expose the functionality within the assembly.
SUBSTRING is positional, but you can use the CHARINDEX function to find the position of each delimiter, and grab the SUBSTRINGs between each comma.
It's a clunky solution, to be sure, but the impact is minimized given a small static number of fields that always appear in order...
SQL Server isn't very strong in string handling - especially if you cannot use SQL-CLR to help.
You might be better off doing this beforehand, in your client application, using something like FileHelpers, a C# library which very easily imports a CSV and breaks it apart into an object for each row.
Once you have that, you can easily loop through the array of objects you have and insert those individual object properties into a relational table.
I have two SQLite tables, that I would love to join them on a name column. This column contains accented characters, so I am wondering how can I compare them for join. I would like the accents dropped for the comparison to work.
You can influence the comparison of characters (such as ignoring case, ignoring accents) by using a Collation. SQLLite has only a few built in collations, although you can add your own.
SqlLite, Data types, Collating Sequences
SqlLite, Define new Collating Sequence
EDIT:
Given that it seems doubtful if Android supports UDFs and computed columns, here's another approach:
Add another column to your table, normalizedName
When your app writes out rows to your table, it normalizes name itself, removing accents and performing other changes. It saves the result in normalizedName.
You use normalizedName in your join.
As the normalization function is now in java, you should have few restrictions in coding it. Several examples for removing accents in java are given here.
There is an easy solution, but not very elegant.
Use the REPLACE function, to remove your accents. Exemple:
SELECT YOUR_COLUMN FROM YOUR_TABLE WHERE replace(replace(replace(replace(replace(replace(replace(replace(
replace(replace(replace( lower(YOUR_COLUMN), 'á','a'), 'ã','a'), 'â','a'), 'é','e'), 'ê','e'), 'í','i'),
'ó','o') ,'õ','o') ,'ô','o'),'ú','u'), 'ç','c') LIKE 'SEARCH_KEY%'
Where SEARCH_KEY is the key word that you wanna find on the column.
As mdma says, a possible solution would be a User-Defined-Function (UDF). There is a document here describing how to create such a function for SQLite in PHP. You could write a function called DROPACCENTS() which drops all the accents in the string. Then, you could join your column with the following code:
SELECT * FROM table1
LEFT JOIN table2
ON DROPACCENTS(table1.column1) = DROPACCENTS(table2.column1)
Much similar to how you would use the UCASE() function to perform a case-insensitive join.
Since you cannot use PHP on Android, you would have to find another way to create the UDF. Although it has been said that creating a UDF is not possible on Android, there is another Stack Overflow article claiming that a content provider could do the trick. The latter sounds slightly complicated, but promising.
Store a special "neutral" column without accented characters and compare / search only this column.