Develop Reference

How to export to CSV file from PostgreSQL using BufferedWriter in Java

I am preparing a batch of SQL PreparedStatement in the following format to export data to CSV files.
COPY (SELECT ..... FROM ..... LIMIT 500 OFFSET ...) TO STDOUT (format 'csv', delimiter ',') '|'
Now I want to hook BufferedWriter to the above SQL statement so that output goes to the specified file. Any suggestions on how to do this?

I'm not sure you really need this construction. In fact, you have two goals to achive: read data from database, and write it to file.
Example of using JDBC in PostgreSQL is here: https://jdbc.postgresql.org/documentation/head/query.html
Example of writing data to file: https://jdbc.postgresql.org/documentation/head/query.html
Just combine them together.

Java insert bit data to Mysql [duplicate]

I have an unnormalized events-diary CSV from a client that I'm trying to load into a MySQL table so that I can refactor into a sane format. I created a table called 'CSVImport' that has one field for every column of the CSV file. The CSV contains 99 columns , so this was a hard enough task in itself:
CREATE TABLE 'CSVImport' (id INT);
ALTER TABLE CSVImport ADD COLUMN Title VARCHAR(256);
ALTER TABLE CSVImport ADD COLUMN Company VARCHAR(256);
ALTER TABLE CSVImport ADD COLUMN NumTickets VARCHAR(256);
...
ALTER TABLE CSVImport Date49 ADD COLUMN Date49 VARCHAR(256);
ALTER TABLE CSVImport Date50 ADD COLUMN Date50 VARCHAR(256);
No constraints are on the table, and all the fields hold VARCHAR(256) values, except the columns which contain counts (represented by INT), yes/no (represented by BIT), prices (represented by DECIMAL), and text blurbs (represented by TEXT).
I tried to load data into the file:
LOAD DATA INFILE '/home/paul/clientdata.csv' INTO TABLE CSVImport;
Query OK, 2023 rows affected, 65535 warnings (0.08 sec)
Records: 2023 Deleted: 0 Skipped: 0 Warnings: 198256
SELECT * FROM CSVImport;
| NULL | NULL | NULL | NULL | NULL |
...
The whole table is filled with NULL.
I think the problem is that the text blurbs contain more than one line, and MySQL is parsing the file as if each new line would correspond to one databazse row. I can load the file into OpenOffice without a problem.
The clientdata.csv file contains 2593 lines, and 570 records. The first line contains column names. I think it is comma delimited, and text is apparently delimited with doublequote.
UPDATE:
When in doubt, read the manual: http://dev.mysql.com/doc/refman/5.0/en/load-data.html
I added some information to the LOAD DATA statement that OpenOffice was smart enough to infer, and now it loads the correct number of records:
LOAD DATA INFILE "/home/paul/clientdata.csv"
INTO TABLE CSVImport
COLUMNS TERMINATED BY ','
OPTIONALLY ENCLOSED BY '"'
ESCAPED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 LINES;
But still there are lots of completely NULL records, and none of the data that got loaded seems to be in the right place.

Use mysqlimport to load a table into the database:
mysqlimport --ignore-lines=1 \
--fields-terminated-by=, \
--local -u root \
-p Database \
TableName.csv
I found it at http://chriseiffel.com/everything-linux/how-to-import-a-large-csv-file-to-mysql/
To make the delimiter a tab, use --fields-terminated-by='\t'

The core of your problem seems to be matching the columns in the CSV file to those in the table.
Many graphical mySQL clients have very nice import dialogs for this kind of thing.
My favourite for the job is Windows based HeidiSQL. It gives you a graphical interface to build the LOAD DATA command; you can re-use it programmatically later.
Screenshot: "Import textfile" dialog
To open the Import textfile" dialog, go to Tools > Import CSV file:

Simplest way which I have imported 200+ rows is below command in phpmyadmin sql window
I have a simple table of country with two columns
CountryId,CountryName
here is .csv data
here is command:
LOAD DATA INFILE 'c:/country.csv'
INTO TABLE country
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS
Keep one thing in mind, never appear , in second column, otherwise your import will stop

I Used this method to import more than 100K records (~5MB) in 0.046sec
Here's how you do it:
LOAD DATA LOCAL INFILE
'c:/temp/some-file.csv'
INTO TABLE your_awesome_table
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
(field_1,field_2 , field_3);
It is very important to include the last line , if you have more than one field i.e normally it skips the last field (MySQL 5.6.17)
LINES TERMINATED BY '\n'
(field_1,field_2 , field_3);
Then, assuming you have the first row as the title for your fields, you might want to include this line also
IGNORE 1 ROWS
This is what it looks like if your file has a header row.
LOAD DATA LOCAL INFILE
'c:/temp/some-file.csv'
INTO TABLE your_awesome_table
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS
(field_1,field_2 , field_3);

phpMyAdmin can handle CSV import. Here are the steps:
Prepare the CSV file to have the fields in the same order as the MySQL table fields.
Remove the header row from the CSV (if any), so that only the data is in the file.
Go to the phpMyAdmin interface.
Select the table in the left menu.
Click the import button at the top.
Browse to the CSV file.
Select the option "CSV using LOAD DATA".
Enter "," in the "fields terminated by".
Enter the column names in the same order as they are in the database table.
Click the go button and you are done.
This is a note that I prepared for my future use, and sharing here if someone else can benefit.

If you are using MySQL Workbench (currently 6.3 version) you can do this by:
Right click on "Tables";
Chose Table Data Import Wizard;
Chose your csv file and follow the instructions (JSON also could be used);
The good thing is that you can create a new table based on the csv file you want to import or load data to an existing table

You can fix this by listing the columns in you LOAD DATA statement. From the manual:
LOAD DATA INFILE 'persondata.txt' INTO TABLE persondata (col1,col2,...);
...so in your case you need to list the 99 columns in the order in which they appear in the csv file.

Try this, it worked for me
LOAD DATA LOCAL INFILE 'filename.csv' INTO TABLE table_name FIELDS TERMINATED BY ',' ENCLOSED BY '"' IGNORE 1 ROWS;
IGNORE 1 ROWS here ignores the first row which contains the fieldnames. Note that for the filename you must type the absolute path of the file.

I see something strange. You are using for ESCAPING the same character you use for ENCLOSING. So the engine does not know what to do when it founds a '"' and I think that is why nothing seems to be in the right place.
I think that if you remove the line of ESCAPING, should run great. Like:
LOAD DATA INFILE "/home/paul/clientdata.csv"
INTO TABLE CSVImport
COLUMNS TERMINATED BY ','
OPTIONALLY ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 LINES;
Unless you analyze (manually, visually, ... ) your CSV and find which character uses for escape. Sometimes is '\'. But if you do not have it, do not use it.

The mysql command line is prone to too many problems on import. Here is how you do it:
use excel to edit the header names to have no spaces
save as .csv
use free Navicat Lite Sql Browser to import and auto create a new table (give it a name)
open the new table insert a primary auto number column for ID
change the type of the columns as desired.
done!

Yet another solution is to use csvsql tool from amazing csvkit suite.
Usage example:
csvsql --db mysql://$user:$password#localhost/$database --insert --tables $tablename $file
This tool can automatically infer the data types (default behavior), create table and insert the data into the created table. --overwrite option can be used to drop table if it already exists. --insert option — to populate the table from the file.
To install the suite
pip install csvkit
Prerequisites: python-dev, libmysqlclient-dev, MySQL-python
apt-get install python-dev libmysqlclient-dev
pip install MySQL-python

In case if you using Intellij
https://www.jetbrains.com/datagrip/features/importexport.html

I use mysql workbench to do the same job.
create new schema
open newly created schema
right click on "Tables" and select "Table Data Import Wizard"
give the csv file path and table name and finally configure your column type because the wizard set default column type based on their values.
Note: take a look at mysql workbench's log file for any errors by using "tail -f [mysqlworkbenchpath]/log/wb*.log"

How to import csv files to sql tables
Example file: Overseas_trade_index data CSV File
Steps:
Need to create table for overseas_trade_index.
Need to create columns related to csv file.
SQL Query:
( id int not null primary key auto_increment,
series_reference varchar (60),
period varchar (60),
data_value decimal(60,0),
status varchar (60),
units varchar (60),
magnitude int(60),
subject text(60),
group text(60),
series_title_1 varchar (60),
series_title_2 varchar (60),
series_title_3 varchar (60),
series_title_4 varchar (60),
series_title_5 varchar (60),
);
Need to connect mysql database in terminal.
=>show databases;
=>use database;
=>show tables;
Please enter this command to import the csv data to mysql tables.
load data infile '/home/desktop/Documents/overseas.csv' into table trade_index fields terminated by ',' lines terminated by '\n' (series_reference,period,data_value,status,units,magnitude,subject,series_title1,series_title_2,series_title_3,series_title_4,series_title_5);
Find this overseas trade index data on sqldatabase:
select * from trade_index;

If you are using a windows machine with Excel spreadsheet loaded, the new mySql plugin to Excel is phenomenal. The folks at Oracle really did a nice job on that software. You can make the database connection directly from Excel. That plugin will analyse your data, and set up the tables for you in a format consistent with the data. I had some monster big csv files of data to convert. This tool was a big time saver.
http://dev.mysql.com/downloads/windows/excel/
You can make updates from within Excel that will populate to the database online. This worked exceedingly well with mySql files created on ultra inexpensive GoDaddy shared hosting. (Note when you create the table at GoDaddy, you have to select some off-standard settings to enable off site access of the database...)
With this plugin you have pure interactivity between your XL spreadsheet and online mySql data storage.

I know that my answer is late, but I'd like to mention a few other ways to do it.
The easiest one is using command line. The steps will be the following:
Accessing the MySQL CLI by entering the below command:
mysql -u my_user_name -p
Creating a table in the database
use new_schema;
CREATE TABLE employee_details (
id INTEGER,
employee_name VARCHAR(100),
employee_age INTEGER,
PRIMARY KEY (id)
);
Importing the CSV file into a table. We can either mention the file path or store the file in the default directory of the MySQL server.
LOAD DATA INFILE 'Path to the exported csv file'
INTO TABLE employee_details
FIELDS TERMINATED BY ','
IGNORE 1 ROWS;
It's the only one of many solutions, I found it in this tutorial
If loading CSV files into MySQL database is your daily task, then it'll be better to automate this process. In this case you can use some 3rd-party tools that allows you to load data in schedule.

PHP Query for import csv file to mysql database
$query = <<<EOF
LOAD DATA LOCAL INFILE '$file'
INTO TABLE users
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
IGNORE 1 LINES
(name,mobile,email)
EOF;
if (!$result = mysqli_query($this->db, $query))
{
exit(mysqli_error($this->db));
}
**Sample CSV file data **
name,mobile,email
Christopher Gritton,570-686-3439,ChristopherKGritton#inbound.plus
Brandon Wilson,541-309-5149,BrandonMWilson#inbound.plus
Craig White,516-795-8065,CraigJWhite#inbound.plus
David Whitney,713-214-3966,DavidCWhitney#inbound.plus

Here is sample excel file screen shot:
Save as and choose .csv.
And you will have as shown below .csv data screen shot if you open using notepad++ or any other notepad.
Make sure you remove header and have column alignment in .csv as in mysql Table.
Replace folder_name by your folder name
LOAD DATA LOCAL INFILE
'D:/folder_name/myfilename.csv'
INTO TABLE mail
FIELDS TERMINATED BY ','
(fname,lname ,email, phone);
If big data, you can take coffee and have it load!.
Thats all you need.

Change servername,username, password,dbname,path of your file, tablename and the field which is in your database you want to insert
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "bd_dashboard";
//For create connection
$conn = new mysqli($servername, $username, $password, $dbname);
$query = "LOAD DATA LOCAL INFILE
'C:/Users/lenovo/Desktop/my_data.csv'
INTO TABLE test_tab
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
IGNORE 1 LINES
(name,mob)";
if (!$result = mysqli_query($conn, $query)){
echo '<script>alert("Oops... Some Error occured.");</script>';
exit();
//exit(mysqli_error());
}else{
echo '<script>alert("Data Inserted Successfully.");</script>'
}
?>

I did it in simple way using phpmyadmin. I followed the steps by #Farhan but all data were eltered in single column.
How I did:
Created a CSV file and deleted the header row with column names. Kept only data.
I created a table with column names matching the csv columns.
Remember to assign appropriate types to each column.
I just selected the import and went to import tab.
In browse I selected the CSV file and kept all options as it is.
To my surprise all the data got imported successfully in their appropriate columns.

When executing MySQL Query to import CSV I was getting error
'Error Code: 1290. The MySQL server is running with the --secure-file-priv option so it cannot execute this statement'
So I moved file to secure file location
LOAD DATA INFILE 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/Orders.csv'
INTO TABLE orderdetails.orders
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS
Where location of file is 'C:/ProgramData/MySQL/MySQL Server 8.0/Uploads/Orders.csv' this is because, I moved my CSV file to 'secure_file_priv' location otherwise I was getting above error
You can get your secure_file_priv using query SHOW VARIABLES LIKE "secure_file_priv";
Source: Import CSV file to MySQL (Query or using Workbench)

Retrieving Hive Table Location using Java

Is there a way to retrieve hdfs location of a hive table using
Java jdbc.
For example:
I have a temporary table t1.
at location '/user/tables_list/t1';
I want to retrieve this location using java code.

As far as I've tried, there isn't a direct way to do this. But, once you've set up your JDBC connection you can execute a "DESCRIBE EXTENDED ", which (in the test I did) will list the table columns for:
res = stmt.executeQuery("DESCRIBE EXTENDED tweets");
while(res.next()){
System.out.println(res.getString(1));
}
but, for the last row, you'll need to use:
res.getString(2)
which will give you a detailed table description that you'll need to parse, but somewhere in there there's a a location field
location:hdfs://localhost:8020/user/hive/warehouse/social.db/tweets
The problem with this, is that is a lot of handwork, because methods like:
res.last()
or
res.isLast()
are not supported, and they would be of a lot of help.

I had the same requirement and I used HiveMetaStoreClient API and it makes it as easy as typing:
srcTable.getSd().getLocation();
srcTable should be the table object which is retrieved from Hive metastore by giving the table specifications.

Cannot read an SQLite Database made in another language

I have an SQLite3 databse I created in python. And by default it writes the database in Unicode.
Now I am trying to query the database in a Java Applet using SQLite JDBC. And I cannot find tables, rows etc because I think Java &/or JDBC queries in ANSI.
Does anyone know how I can query my SQLite3 DB with a unicode query in Java? Something like the following doesn't work (in Java trying to execute a Unicode SQL query):
If I access the database in python I can print out the tables no problem & make updates BUT if I try to do the same in Java, I get no results returned from my query. Is this an encoding problem or some thing else
This works import sqlite3
def blah():
conn = sqlite3.connect( "a.db" )
cur = conn.cursor()
res = cur.execute( "SELECT name FROM sqlite_master WHERE type='table'" ).fetchal()
print res
blah()
This returns no tables when it should return the same tables as above
Class.forName("org.sqlite.JDBC");
Connection conn = DriverManager.getConnection("jdbc:sqlite:a.db");
Statement stat = conn.createStatement();
conn.setAutoCommit(false);
ResultSet tables = stat.executeQuery("SELECT name FROM sqlite_master WHERE type='table'");
String b = "";
while (tables.next()) { b+= "table= " + tables.getString("name"); }

Jim, that's very odd, it should work. Have you tried to open the DB from the console?
you can open it by running sqlite3 a.db
something that intrigues me, is that you're trying to open the db from a java applet. Have you given it the necessary permissions and signed it, so the apple can actually write to disk?

Have your tired opening the sqlite3 a.db and typing PRAGMA encoding; ? It should say UTF8 by default.
I am able to create a UTF8 sqlite database on the command line and read the contents of that file using sqlite jdbc.
Are you sure you are connecting to the database that you created with python? IF the database does not exist then sqlite will create the database and it will not have any tables in it. This is what is probably happening to you.
Are you running the java and python in the same directory?

Parsing data into tables

I have created a connection with Mysql and java program via jdbc. Now I want to populate the tables in the mysql database. How do I parse the data into the tables from the java code?
I have two input data files.The format of file is like:
"AAH196","17:13:00","02:49:00",287,166.03,"Austin","TX","Virginia Beach","VA"
"AAH3727","21:38:00","03:04:00",273,176.44,"Los Angeles","CA","Colorado Springs","CO"

You can use the LOAD DATA INFILE SQL command.

An easy solution: read a single line an use the content as a part of an SQL INSERT command:
List<String> lines = getAllLinesFromFile(file);
for (String line: lines) {
String query = "INSERT INTO \"TABLE\" (COL1, ..., COL9) VALUES("+line+");";
stmt.executeUpdate(query);
}
Replace TABLE with your actual tablename and COL1, ..., COL9 with an enumeration of your column names. There may be solutions with a better database performance (like using prepared statements) but the algorithm is easy and sufficient to get some data into the database.