Add a primary key to a sqlite table

100%

Add a primary key to a sqlite table

✓ Published0🌍 Public

Last edited Nov 17, 2017

Created on Nov 17, 2017

This example demonstrates a SQLite migration technique that adds a primary key to an existing table without losing its data. The code defines three functions: `get_create_table_string` retrieves the original `CREATE TABLE` statement from the `sqlite_master` system table, `add_pk_to_create_table_string` uses the `re` module’s `re.sub` to insert the `PRIMARY KEY` constraint into that string for a specified column, and `add_pk_to_sqlite_table` orchestrates the migration. It executes an SQL `BEGIN TRANSACTION` block that renames the original table, creates a new table using the modified schema, copies rows via `INSERT INTO ... SELECT *`, and drops the old table. The example uses Python’s `sqlite3` connection API and `executescript` to run the multi-statement transaction.

AI-generated description

Similar vizzes

Loading thumbnail…

SQLite cursus Udemy

This example demonstrates how to manage SQLite databases through Python, contrasting two distinct approaches. It shows the creation, insertion, and querying of database tables using both the SQLAlchemy ORM and the raw `sqlite3` module. The code highlights SQLAlchemy’s declarative table definitions, `db.insert()` for record insertion, and `pd.read_sql_query` to load query results into a pandas DataFrame. It also presents `sqlite3` with cursor-based operations like `execute()` for CRUD functions and parameterized queries for email lookups. The visualization is purely programmatic, with no graphical output, focusing instead on code patterns for database interaction.

FFrieseWoudloper

55% match

Loading thumbnail…

Add new column in PostgreSQL with a subquery and set a NOT NULL constraint

This example shows how to add a new column to an existing PostgreSQL table and populate it with values from another table using a subquery in an UPDATE statement. The SQL script begins by adding the `exp_id` column as type `text`, then updates it by joining `table1` with `table2` on the `gid` field to copy matching `exp_id` values. Finally, it alters the column to set a `NOT NULL` constraint and wraps all operations in a single transaction with `BEGIN` and `COMMIT` to ensure atomicity. The code relies on standard PostgreSQL DDL and DML commands without external APIs.

LLuisSevillano

50% match

Loading thumbnail…

Gist e9eac02df35654daa5d0

This example demonstrates a minimal data pipeline that reads JSON data and inserts it into a local SQLite database. The script, `jsonToSqlite.py`, loads a JSON file containing a list of objects, extracts the first object’s `"foo"` and `"bar"` fields, and writes those two values as a single row into a table named `table_name`. It uses the standard `json` module for parsing and `sqlite3` for database operations, creating a table and inserting the data with a parameterized `execute` call. The visualization shows only the code structure, not a graphical output, highlighting the simple ETL pattern of extracting, transforming, and loading data.

CCBasis

49% match

Loading thumbnail…

A schema for uploading MOT test data, as suggested in the user guide with the exception of the `SET storage_engine=MyISAM` which is there to allow the `ENABLE KEYS\DISABLE KEYS` mechanism used in the large table uploads. Also the field `RFRINSPMANDESC TEXT(500) #Variation from suggested schema due to 1074 error` is suggested as `char` in the user guide but for my MySQL setup this exceeds the allowed size for char.

This schema defines the relational structure for importing UK MOT test data, showing the primary tables for test results, test items, item details, item groups, and failure locations. It demonstrates the use of MySQL DDL with explicit primary keys, composite indexes, and the MyISAM storage engine to enable bulk-loading optimizations. The code highlights practical deviations from the official user guide, such as using `TEXT(500)` for inspection descriptions instead of an oversized `CHAR`, accommodating MySQL’s row-size limits while preserving data integrity.

IIanHopkinson

45% match

Loading thumbnail…

Concept for inserting data into SQL Server

This example demonstrates a concept for inserting data into SQL Server by using Power Query’s M language. It shows a table creation script for a demo table with an identity column, a key, and a value, followed by an M query that iterates over a list of key-value pairs. The code uses `List.Accumulate` to loop through the pairs and calls `OleDb.DataSource` with a SQL `INSERT` statement for each iteration, referencing the SQLOLEDB provider to connect to a local database. The result is the total number of affected records from the inserts, though the actual inserted rows are not visualized or returned in the output.

HHugoberry

45% match

Loading thumbnail…

SQL to upload the smaller tables of the MOT test dataset

This example demonstrates how to prepare smaller reference tables from the MOT test dataset for database loading, showing the SQL commands that import three text files—failure_location, item_detail, and item_group—into their corresponding MySQL tables. The script uses the `LOAD DATA LOCAL INFILE` API to parse pipe-delimited files with newline-terminated records, explicitly specifying field and line terminators. The code relies on standard SQL syntax within a MySQL environment, first selecting the MOT database with `USE MOT` before executing each import. This approach highlights a straightforward, file-based data ingestion pattern rather than a visual rendering technique, focusing on the database population step that precedes any charting or visualization work.

IIanHopkinson

44% match

Loading thumbnail…

copy to temp table method for updating addressbase

This example demonstrates a PostgreSQL method for efficiently replacing the contents of a large AddressBase database table by loading incoming CSV data into temporary tables, building indexes and constraints there, and then using a transactional rename swap to minimize downtime. The script first copies data from `addressbase_cleaned.csv` and `uprn-to-councils.csv` into empty temp tables, then adds primary keys, GiST spatial indexes on `location`, and B-tree indexes on `postcode` and `uprn`. Within a `BEGIN`/`COMMIT` block, it drops foreign keys, renames the existing tables to `_old`, promotes the temp tables to the main names, and re-adds the foreign key constraints. Timings for each operation illustrate the relative cost of loading, indexing, and swapping.

GGeoWill

43% match

Loading thumbnail…

Gist d2f55e96546318a1e8e393d423ea36e9

This example shows a SQL query that transfers data from one Excel sheet to another, creating a new table in a separate workbook file. The visualization demonstrates how data can be exported or copied between spreadsheet locations using an embedded query. The code uses the `SELECT * INTO` syntax with an `[Excel 8.0;DATABASE=...]` connection string, specifying the destination file path and sheet name. The query pulls all records from the source sheet and writes them to the target workbook, illustrating a straightforward data-migration pattern. The rendering approach relies on the database driver’s handling of the Excel file format, with no additional charting or graphics libraries involved.

HHugoberry

42% match