As the title says: I've got a bunch of tab-separated text files containing data.
I know that if I use 'CREATE TABLE' statements to set up all the tables manually, I can then import them into the waiting tables, using 'load data' or 'mysqlimport'.
But is there any way in MySQL to create tables automatically based on the tab files? Seems like there ought to be. (I know that MySQL might have to guess the data type of each column, but you could specify that in the first row of the tab files.)
No, there isn't. You need to CREATE a TABLE first in any case.
Automatically creating tables and guessing field types is not part of the DBMS's job. That is a task best left to an external tool or application (That then creates the necessary CREATE statements).
If your willing to type the data types in the first row, why not type a proper CREATE TABLE statement.
Then you can export the excel data as a txt file and use
LOAD DATA INFILE 'path/file.txt' INTO TABLE your_table;
Related
I was given an excel (csv) sheet containing a database metadata.
I'm asking if there's a simple way to import the csv and create the tables from there?
Data is not part of this question. the csv looks like this:
logical_table_name, physical_table_name, logical_column_name, physcial_column_name, data_type, data_length
There's about 2000 rows of metadata. I'm hoping I don't have to manually create the tables. Thanks.
I don't know of any direct import or creation. However, if I had to do this and I couldn't find one, I would import the excel file into a staging table (just a direct data import). I'd make add a unique auto ID column to staging table to keep the rows in order.
Then I would use some queries to build table and column creation commands from the raw data. Unless this was something I was setting up to do a lot, I would keep it dead simple, not try and get fancy. Build individual add column commands for each column. Build a create Table command for the first row for each table. Sort them all by the order id, tables before columns. Then you should be able to just copy the script column, check the commands, and go.
Is there a way to import a csv into a SQL table, without having a previously-constructed table? I know how to import a csv into an existing table, but is there a way to create one from the csv?
You can do this using phpMyAdmin ,
(in this method csv file first row elements use as column names for the sql table)
1) select database
2) go to import tab and select csv file
3) ↓↓↓↓↓↓↓
4) after above steps new table will be created and if you want to change table names instead of having table1,table2
select table and go to operation tab :)
(phpMyAdmin 4.1.14)
I am no expert in MySQL but I don't believe there is such an import process. And there might not be in other database servers like Oracle, SQL Server, or PostgreSQL. In fact, it may not be a desirable automation as a table should be user defined and created to fit the database's relational model and for appropriate data types, indices, and keys.
Almost all SQL dialects require setting up the database table beforehand. If not, how would the system know beforehand you intended an integer or long number, a double or decimal number, a tinytext or longtext, which fields are to be indexed, or serve as primary key, and so on?
You might argue MS Access allows a CSV import with an optional table name. However, the ribbon wizard walks the user through setting up the field types, primary key, and table name. And going the non-wizard automation route, the DoCmd.TransferText method requires table name when using the acImportDelim argument.
So, your best process in MySQL may be LOAD DATA INFILE to run a bulk import of an external CSV into an existing table.
From the docs, it states:
The CSV storage engine stores data in text files using comma-separated
values format.
What are the advantages of this? Here are some I can think of:
You can edit the CSV files using simple text editor (however, you can export data easily using SELECT INTO OUTFILE)
Can be easily imported into Spreadsheet programs
Lightweight and maybe better performance (wild guess)
What are some disadvantages?
No indexing
Cannot be partitioned
No transactions
Cannot have NULL values
Granted this (non-exhaustive) list of advantages and disadvantages, in what practical scenarios should I consider using the CSV storage engine over others?
I seldom use the CSV storage engine. One scenario I have found it useful, however, is for bulk data imports.
Create a table with columns matching my input CSV file.
Outside of mysql, just using a shell prompt, mv the CSV file into the MySQL data dictionary, overwriting the .csv file that belongs to my table I just created.
ALTER TABLE mytable ENGINE=InnoDB
Voilà! One-step import of a huge CSV data file using DDL instead of INSERT or LOAD DATA.
Granted, it's less flexible than INSERT or LOAD DATA, because you can't do NULLs or custom overrides of individual columns, or any "replace" or "ignore" features for handling duplicate values. But if you have an input file that is exactly what you want to import, it could make the import very easy.
This is a tad bit hacky, but as of MySQL 8, assuming you know the data structure beforehand and have permissions in the CSV-based schema directory, you can create the table definition in MySQL and then overwrite the generated CSV table file in the data directory with a symlink to the data file:
mysql --execute="CREATE TABLE TEST.CSV_TEST ( test_col VARCHAR(255) ) ENGINE=CSV;"
ln -sf /path/to/data.file /var/lib/mysql/TEST/CSV_TEST.CSV
An advantage here is that this completely obviates the need to run import operations (via LOAD DATA INFILE, etc.), as it allows MySQL to read directly from the symlinked file as if it were the table file.
Drawbacks beyond those inherent to the CSV engine:
table will contain header row if there is one (you'd need to filter it out from read operations)
table metadata in INFORMATION_SCHEMA will not update using this method, will just show the CREATE_TIME for which the initial DDL is run
Note this method is obviously more geared toward READ operations, though update/insert operations could be conducted on the command line using SELECT ... INTO OUTFILE and then copying onto/appending the source file.
Another posting said there is a way to infer the table columns from a data file using phpMyAdmin. I haven't found documentation on this, can you point me to it? Does it only use the header row, or does it also sample the data to infer the data type?
I'm trying to create several tables in MySQL from data files, which have roughly 100 columns each, so I don't want to write the SQL DDL to create the tables manually.
Thanks!
I hava text file full of values like this:
The first line is a list of column names like this:
col_name_1, col_name_2, col_name_3 ......(600 columns)
and all the following columns have values like this:
1101,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1101,1,3.86,65,0.46418,65,0.57151...
What is the best way to import this into mysql?
Specifically how to come up with the proper CREATE TABLE command so that the data will load itself properly? What is the best generic data type which would take in all the above values like 1101 or 3.86 or 0.57151. I am not worried about the table being inefficient in terms of storage as I need this for a one time usage.
I have tried some of the suggestions in other related questions like using Phpmyadmin (it crashes I am guessing due to the large amount of data)
Please help!
Data in CSV files is not normalized; those 600 columns may be spread across a couple of related tables. This is the recommended way of treating those data. You can then use fgetcsv() to read CSV files line-by-line in PHP.
To make MySQL process the CSV, you can create a 600 column table (I think) and issue a LOAD DATA LOCAL INFILE statement (or perhaps use mysqlimport, not sure about that).
The most generic data type would have to be VARCHAR or TEXT for bigger values, but of course you would lose semantics when used on numbers, dates, etc.
I noticed that you included the phpmyadmin tag.
PHPMyAdmin can handle this out of box. It will decide "magically" which types to make each column, and will CREATE the table for you, as well as INSERT all the data. There is no need to worry about LOAD DATA FROM INFILE, though that method can be more safe if you want to know exactly what's going on without relying on PHPMyAdmin's magic tooling.
Try convertcsvtomysql, just upload your csv file and then you can download and/or copy the mysql statement to create the table and insert rows.