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======
csvsql
======
Description
===========
Generate SQL statements for a CSV file or execute those statements directly on a database. In the latter case supports both creating tables and inserting data:
.. code-block:: none
usage: csvsql [-h] [-d DELIMITER] [-t] [-q QUOTECHAR] [-u {0,1,2,3}] [-b]
[-p ESCAPECHAR] [-z FIELD_SIZE_LIMIT] [-e ENCODING] [-L LOCALE]
[-S] [--blanks] [--null-value NULL_VALUES [NULL_VALUES ...]]
[--date-format DATE_FORMAT] [--datetime-format DATETIME_FORMAT]
[-H] [-K SKIP_LINES] [-v] [-l] [--zero] [-V]
[-i {firebird,mssql,mysql,oracle,postgresql,sqlite,sybase}]
[--db CONNECTION_STRING] [--query QUERIES] [--insert]
[--prefix PREFIX] [--before-insert BEFORE_INSERT]
[--after-insert AFTER_INSERT] [--tables TABLE_NAMES]
[--no-constraints] [--unique-constraint UNIQUE_CONSTRAINT]
[--no-create] [--create-if-not-exists] [--overwrite]
[--db-schema DB_SCHEMA] [-y SNIFF_LIMIT] [-I]
[--chunk-size CHUNK_SIZE]
[FILE [FILE ...]]
Generate SQL statements for one or more CSV files, or execute those statements
directly on a database, and execute one or more SQL queries.
positional arguments:
FILE The CSV file(s) to operate on. If omitted, will accept
input as piped data via STDIN.
optional arguments:
-h, --help show this help message and exit
-i {mssql,mysql,oracle,postgresql,sqlite,duckdb,crate,ingres}, --dialect {mssql,mysql,oracle,postgresql,sqlite,duckdb,crate,ingres}
Dialect of SQL to generate. Cannot be used with --db.
--db CONNECTION_STRING
If present, a SQLAlchemy connection string to use to
directly execute generated SQL on a database.
--engine-option ENGINE_OPTION ENGINE_OPTION
A keyword argument to SQLAlchemy's create_engine(), as
a space-separated pair. This option can be specified
multiple times. For example: thick_mode True
--query QUERIES Execute one or more SQL queries delimited by --sql-
delimiter, and output the result of the last query as
CSV. QUERY may be a filename. --query may be specified
multiple times.
--insert Insert the data into the table. Requires --db.
--prefix PREFIX Add an expression following the INSERT keyword, like
OR IGNORE or OR REPLACE.
--before-insert BEFORE_INSERT
Before the INSERT command, execute one or more SQL
queries delimited by --sql-delimiter. Requires
--insert.
--after-insert AFTER_INSERT
After the INSERT command, execute one or more SQL
queries delimited by --sql-delimiter. Requires
--insert.
--sql-delimiter SQL_DELIMITER
Delimiter separating SQL queries in --query, --before-
insert, and --after-insert.
--tables TABLE_NAMES A comma-separated list of names of tables to be
created. By default, the tables will be named after
the filenames without extensions or "stdin".
--no-constraints Generate a schema without length limits or null
checks. Useful when sampling big tables.
--unique-constraint UNIQUE_CONSTRAINT
A column-separated list of names of columns to include
in a UNIQUE constraint.
--no-create Skip creating the table. Requires --insert.
--create-if-not-exists
Create the table if it does not exist, otherwise keep
going. Requires --insert.
--overwrite Drop the table if it already exists. Requires
--insert. Cannot be used with --no-create.
--db-schema DB_SCHEMA
Optional name of database schema to create table(s)
in.
-y SNIFF_LIMIT, --snifflimit SNIFF_LIMIT
Limit CSV dialect sniffing to the specified number of
bytes. Specify "0" to disable sniffing entirely, or
"-1" to sniff the entire file.
-I, --no-inference Disable type inference (and --locale, --date-format,
--datetime-format, --no-leading-zeroes) when parsing
the input.
--chunk-size CHUNK_SIZE
Chunk size for batch insert into the table. Requires
--insert.
--min-col-len MIN_COL_LEN
The minimum length of text columns.
--col-len-multiplier COL_LEN_MULTIPLIER
Multiply the maximum column length by this multiplier
to accomodate larger values in later runs.
See also: :doc:`../common_arguments`.
For information on connection strings and supported dialects refer to the `SQLAlchemy documentation <https://www.sqlalchemy.org/docs/dialects/>`_.
If you prefer not to enter your password in the connection string, store the password securely in a `PostgreSQL Password File <https://www.postgresql.org/docs/9.1/static/libpq-pgpass.html>`_, a `MySQL Options File <https://dev.mysql.com/doc/refman/5.7/en/option-files.html>`_ or similar files for other systems.
.. note::
Using the :code:`--query` option may cause rounding (in Python 2) or introduce `Python floating point issues <https://docs.python.org/3/tutorial/floatingpoint.html>`_ (in Python 3).
.. note::
If the CSV file was created from a JSON file using :doc:`in2csv`, remember to quote SQL columns properly. For example:
.. code-block:: bash
echo '{"a":{"b":"c"},"d":"e"}' | in2csv -f ndjson | csvsql --query 'SELECT "a/b" FROM stdin'
.. note::
Alternatives to :doc:`csvsql` are `q <https://github.com/harelba/q>`_ and `textql <https://github.com/dinedal/textql>`_.
Examples
========
Generate SQL statements
-----------------------
Generate a statement in the PostgreSQL dialect:
.. code-block:: bash
csvsql -i postgresql examples/realdata/FY09_EDU_Recipients_by_State.csv
Interact with a SQL database
----------------------------
Create a table and import data from the CSV directly into PostgreSQL:
.. code-block:: bash
createdb test
csvsql --db postgresql:///test --tables fy09 --insert examples/realdata/FY09_EDU_Recipients_by_State.csv
For large tables it may not be practical to process the entire table. One solution to this is to analyze a sample of the table. In this case it can be useful to turn off length limits and null checks with the :code:`--no-constraints` option:
.. code-block:: bash
head -n 20 examples/realdata/FY09_EDU_Recipients_by_State.csv | csvsql --no-constraints --tables fy09
Create tables for an entire directory of CSVs and import data from those files directly into PostgreSQL:
.. code-block:: bash
createdb test
csvsql --db postgresql:///test --insert examples/*_converted.csv
If those CSVs have identical headers, you can import them into the same table by using :doc:`csvstack` first:
.. code-block:: bash
createdb test
csvstack examples/dummy?.csv | csvsql --db postgresql:///test --insert
Query and output CSV files using SQL
------------------------------------
You can use csvsql to "directly" query one or more CSV files. Please note that this will create an in-memory SQLite database, so it won't be very fast:
.. code-block:: bash
csvsql --query "SELECT m.usda_id, avg(i.sepal_length) AS mean_sepal_length FROM iris AS i JOIN irismeta AS m ON (i.species = m.species) GROUP BY m.species" examples/iris.csv examples/irismeta.csv
Group rows by one column:
.. code-block:: bash
csvsql --query "SELECT * FROM 'dummy3' GROUP BY a" examples/dummy3.csv
Concatenate two columns:
.. code-block:: bash
csvsql --query "SELECT a || b FROM 'dummy3'" --no-inference examples/dummy3.csv
If a column contains null values, you must ``COALESCE`` the column:
.. code-block:: bash
csvsql --query "SELECT a || COALESCE(b, '') FROM 'sort_ints_nulls'" --no-inference examples/sort_ints_nulls.csv
The ``UPDATE`` SQL statement produces no output. Remember to ``SELECT`` the columns and rows you want:
.. code-block:: bash
csvsql --query "UPDATE 'dummy3' SET a = 'foo'; SELECT * FROM 'dummy3'" examples/dummy3.csv
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