I am new at databases. I have table and and I need to export it and save its structure. I'm using MySql Workbench. It is my first task and I have no idea and know just few things about databases.
Your question is a bit unprecise. What exactly do you want to export? The table structure + data for later restore (if so use a dump) or just the table data in a common format like CSV for further processing (if so use the table data export wizard).
A dump is what is usually used to store SQL data + structure in text files (conventionally tagged with an .sql extension). These contain Data Definition Language (DDL) constructs which define the meta data (e.g. CREATE TABLE) as well as Data Manipulation Language (DML) commands to manage the content (e.g. INSERT or DELETE). This structure serves well for copying content between servers and such, as it is what a database server speaks natively. In MySQL Workbench you can import and export such dumps via the Management tab -> Data Import/Restore:
For importing and exporting data via a common file format like CSV or JSON, use the table data import/export feature, reachable via the context menu for a given table:
this does however not preserve the structure of the table in a manner which would allow to recreate it automatically (like SQL statements do).
Related
When investigation
I found following answer
How do I generate a SQL script from my diagram in MySQL Workbench?
BUT its generate ALL database tables code into ONLY ONE single SQL script
Any Help to generate the database tables code into Multi Separated SQL script(s)
There is no direct way to exclude or include a specific database in the output script, however you can use a workaround. On the SQL Object Export Filter page you can determine which objects to export. Since it supports multiselection and is sorted alphabetically (so all objects from one schema stay together) you can quickly collect object lists for each schema.
Open (Data Export) by selecting following menu item
Server -> Data Export
Then
Choose your DB schema and its tables which need to be exported
Choose Dump Structure Only
Choose Export option Export to Dump project folder
Finally after customize your export .. click start export
I have two different databases. I have to access data from one database and insert them into another ( with some data processing included, it is not only to copy data ) Also, the schema is really complex and each table has many rows, so copying data into schema in the second database is not an option. I have to do that using MySQL Workbench, so I have to do it using SQL queries. Is there a way to create a connection from one database to another and access its data?
While MySQL Workbench can be used to transfer data between servers (e.g. as part of a migration process) it is not useful when you have to process the data first. Instead you have 2 other options:
Use a dedicated tool you write yourself to do that (as eddwinpaz mentioned).
Use the capabilities of your server. That is, copy the data to the target server, into a temporary table (using dump and restore). Then use queries to modify the data as you need it. Finally copy it to the target 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.
I have 100+ XLSX files that I need to get into a MySQL Database. Each file is a bit different, so I've created a massive table that contains a field for each possible column header across all files. This way they can auto-map on import.
Using Navicat I can import the files one at a time, but I'm wondering if there is a way to import all of the files at one time?
I'm thinking 'no' but if your going to do this a lot I think there are ways to automate this.
Export your xls-files into csv-files instead. Write some script to transform them between csv-excel style to csv-mysql style.
Create tables for importing with the csv engine. Put your files inplace of the ones created by mysql and flush tables. Now your data is ready to be read inside mysql and copied over to more powerful tables engines.
Another way is to do a VBA-script that exports the data in a format recognized by load data infile and then load them using mysql.
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;