I have read access to an Oracle database. I am using cx_Oracle to make queries. One of the table column is a CLOB with XML strings. To speed up the network access I figured I would try to ask the database to first compress the xml data before it sends it because the network link is very slow. Is there any way to do this? I would uncompress the data on my end. Looking for something like:
SELECT COMPRESS(clob_column) AS comp_data
FROM table1
WHERE id=1
Thanks
Related
I want to connect a Node Express API with an Oracle 11g Database which has a table with a BLOB column. I want to read it using a SQL query, but the problem is that the BLOB column can have a very long text, more than 100k characters. How can i do this?
I tried using: select utl_raw.cast_to_varchar2(dbms_lob.substr(COLUMN_NAME)) from TABLE_NAME.
But it returns 'raw variable length too long'.
I can make multiple queries in a loop and then join them if it was necessary, but I haven't found how bring just a part of the blob.
Use the node-oracledb module to access Oracle Database (which you are probably already doing, but don't mention).
By default, node-oracledb will return LOBs as Lob instances that you can stream from. Alternatively you can fetch the data directly as a String or Buffer, which is useful for 'small' LOBs. For 100K, I would just get the data as a Buffer, which you can do by setting:
oracledb.fetchAsBuffer = [ oracledb.BLOB ];
Review the Working with CLOB, NCLOB and BLOB Data documentation, and examples like blobhttp.js and the other lob*.js files in the examples directory.
You may also want to look at https://jsao.io/2018/03/creating-a-rest-api-with-node-js-and-oracle-database/ which shows Express and node-oracledb.
I have a fairly simple CSV file that I would like to use within a SQL query. I'm using Oracle SQL Developer but none of the solutions I have found on the web so far seem to have worked. I don't need to store the data (unless I can use temp tables?) just to query it and show results.
Thank You!
You need to create an EXTERNAL TABLE. This essentially maps a CSV (or indeed any flat file) to a table. You can then use that table in queries. You will not be able to perform DML on the external table.
I have several 100 excel files that are not normalized enough for me to efficiently import into the tables of my database. It is difficult to find information but from what I have seen it is possible to index xlsx files with FTS. I am not really looking to implement an alternate database for this as it is a one time thing that will not receive new data.
Would it be possible to do this with FTS and if so could someone point me in the right direction as the info I've found on msdn is quite vague.
Thanks.
I have done something similar using BULK. I would suggest taking a look at it
http://www.sqlteam.com/article/using-bulk-insert-to-load-a-text-file
How it works is excel data can be taken as a text file. Each column is separated by a ";" and each row by "\n" you can then use BULK to crawl through your excel sheet and insert it in a table.
Note that all the values coming from BULK are text values. So if your table contains int values, for example, you will need a temporary table.
CREATE TABLE #TEMPORARYTABLE(
)
The # creates a table that only exists until you disconnect from sql server.
All values in that table should be nvarchars
You can then insert into your real table the #TEMPORARYTABLE and CAST the Nvarchar values to int values or whatever else you need
FTS is a feature in SQL Server, The data you want to create FTS for needs to in a SQL Server database.
Excel being in Excel and not in SQL Server , you will not be able to create FTS for them Excel sheets.
But if you import that data into SQL Server only then you will be able to make use of FTS features, till then unfortunately FTS is not an option for you.
Nothing technical here. Suppose I have a lot of different categorized data, and I would like to create a database out of it. Would someone literally hand plug in all that info with SQL code itself? Or do some people make a mock website just to input data? What are some of your strategies?
If there would be no way to do it automatically, then a mock website would be the way to go: you can even use it with more people at once, actually multiplying the input speed (as long as you don't mess up assigning each of them a different part of the data).
What format is your data in? And how much of it is there? If its Excel then SQL Server has tools to import it in. I'm not sure if MySQL has anything similar. Even if it doesn't one other technique I have used with Excel data is to use a formula to concatenate as required to generate the INSERT statements. Then just paste those into a query window and run that.
I wouldn't do a website for it unless I was building an admin site for it already and wanted to test that with the initial load.
Most databases have a way to do bulk inserts or have tools for data import.
My strategies normally involve such tools.
Here is an example of importing a CSV file to SQL Server.
Most database servers provide a way to import data from a variety of formats, you could look into that first.
If not, you could write a simple script or console application to parse your input data, and write out a SQL script to insert the data into appropriate tables.
For example, if you data was in a CSV file, you would parse each line in the file, and generate an insert statement to write out to a .sql file.
MyData.csv
1,2,3,'Test',4
2,3,4,'Test2,6
GeneratedInsert.sql
insert into table (col1,col2,col3,col4,col5) values (1,2,3,'Test',4)
insert into table (cal1,col2,col3,col4,col5) values (2,3,4,'Test2',6)
MySQL has a statement LOAD DATA INFILE that is intended for loading bulk data from flat files. It's easy to use and much faster than alternative methods.
But first you do have to use SQL to design tables with fields that match the field of your import data. That is, if you have some file with comma-separated data:
Titanic;1997;4 stars
Batman Begins;2005;5 stars
"Harry Potter and the Sorcerer's Stone";2001;3 stars
...
You would create a table:
CREATE TABLE Movies (
title VARCHAR(100) NOT NULL,
year YEAR NOT NULL
rating VARCHAR(10)
);
Then load data:
LOAD DATA INFILE 'movies.txt' INTO TABLE Movies
FIELDS TERMINATED BY ';' OPTIONALLY ENCLOSED BY '"';
Most web languages have some sort of auto-scaffolding that you can quickly set up. Useful for admin work as well, if your site is hosted without direct access to DB.
Otherwise, yeah - write the SQL statements. Useful to bring a database up as part of your build process.
Is it possible for me to write an SQL query from within PhpMyAdmin that will search for matching records from a .csv file and match them to a table in MySQL?
Basically I want to do a WHERE IN query, but I want the WHERE IN to check records in a .csv file on my local machine, not a column in the database.
Can I do this?
I'd load the .csv content into a new table, do the comparison/merge and drop the table again.
Loading .csv files into mysql tables is easy:
LOAD DATA INFILE 'path/to/industries.csv'
INTO TABLE `industries`
FIELDS TERMINATED BY ';'
IGNORE 1 LINES (`nogaCode`, `title`);
There are a lot more things you can tell the LOAD command, like what char wraps the entries, etc.
I would do the following:
Create a temporary or MEMORY table on the server
Copy the CSV file to the server
Use the LOAD DATA INFILE command
Run your comparison
There is no way to have the CSV file on the client and the table on the server and be able to compare the contents of both using only SQL.
Short answer: no, you can't.
Long answer: you'll need to build a query locally, maybe with a script (Python/PHP) or just uploading the CSV in a table and doing a JOIN query (or just the WHERE x IN(SELECT y FROM mytmmpTABLE...))
For anyone new asking, there is this new tool that i used : Write SQL on CSV file