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  2. Data validation - Wikipedia

    en.wikipedia.org/wiki/Data_validation

    This check is essential for programs that use file handling. Format check Checks that the data is in a specified format (template), e.g., dates have to be in the format YYYY-MM-DD. Regular expressions may be used for this kind of validation. Presence check Checks that data is present, e.g., customers may be required to have an email address ...

  3. SQLAlchemy - Wikipedia

    en.wikipedia.org/wiki/SQLAlchemy

    SQLAlchemy is an open-source Python library that provides an SQL toolkit (called "SQLAlchemy Core") and an Object Relational Mapper (ORM) for database interactions. It allows developers to work with databases using Python objects, enabling efficient and flexible database access.

  4. Check digit - Wikipedia

    en.wikipedia.org/wiki/Check_digit

    The final digit of a Universal Product Code, International Article Number, Global Location Number or Global Trade Item Number is a check digit computed as follows: [3] [4]. Add the digits in the odd-numbered positions from the left (first, third, fifth, etc.—not including the check digit) together and multiply by three.

  5. Luhn algorithm - Wikipedia

    en.wikipedia.org/wiki/Luhn_algorithm

    The check digit is computed as follows: Drop the check digit from the number (if it's already present). This leaves the payload. Start with the payload digits. Moving from right to left, double every second digit, starting from the last digit. If doubling a digit results in a value > 9, subtract 9 from it (or sum its digits).

  6. Checksum - Wikipedia

    en.wikipedia.org/wiki/Checksum

    The simplest checksum algorithm is the so-called longitudinal parity check, which breaks the data into "words" with a fixed number n of bits, and then computes the bitwise exclusive or (XOR) of all those words. The result is appended to the message as an extra word.

  7. Determination of the day of the week - Wikipedia

    en.wikipedia.org/wiki/Determination_of_the_day...

    Take the given date in 4 portions, viz. the number of centuries, the number of years over, the month, the day of the month. Compute the following 4 items, adding each, when found, to the total of the previous items. When an item or total exceeds 7, divide by 7, and keep the remainder only.

  8. Meter Point Administration Number - Wikipedia

    en.wikipedia.org/wiki/Meter_Point_Administration...

    The final digit in the MPAN is the check digit, and validates the previous 12 (the core) using a modulus 11 test. The check digit is calculated thus: Multiply the first digit by 3; Multiply the second digit by the next prime number (5) Repeat this for each digit (missing 11 out on the list of prime numbers for the purposes of this algorithm)

  9. Where (SQL) - Wikipedia

    en.wikipedia.org/wiki/Where_(SQL)

    A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria. The criteria are expressed in the form of predicates. WHERE clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned ...