Row (database)

A record is according to Mertens ( 1998), a group of content -related ( belonging to an object) data fields, eg, item number and item name. The data fields, Name ',' Address ' and ' birth ' could also form a record to a person. Records correspond to a logical structure that was defined during the software development (eg in the conceptual schema of the data modeling ).

In data processing, data records are grouped into databases or files are stored, they are the subject of the processing of computer programs and are generated from these, read, modify, and delete ( CRUD see ). When entering the content of records is often presented in the form of a form with the issue or display in list form, possibly with only part of the data fields.

Even non-electronic data can be grouped into data sets, for example, an index card is in a card file, a record.

In addition to the meaning of " record " in the narrow sense - as a collection of specific data (eg, the address data from customer Müller) - the term is in the context of software development used as a term for the type of data structure ( record address data). Depending on the methodology used, programming languages ​​, etc. instead of record ' also uses other expressions, such as entity / entity type, class, tuples, line, structure, sentence (English Record), composite, etc.

Limitation: Although data almost always occur as Aneinderreihung multiple data elements, it's not called all manifestations of data ' record ', but only data groups belonging to a particular object and which have identical structures within a dataset. Not included as records in this sense, therefore, for example: body copy, print, or video data streams contents of executable files, photo data or the data of graphics software, among others

Colloquial use of the term

While in the relational algebra, relational database systems and computer science in general, the term data set restricted as one-dimensional, structured set of attributes of an element of a superior amount (eg, index card in a card file, address bar, etc. in an address list ) is defined, is the term record ' colloquially and medial frequently ( and incorrectly in the singular ) is used in a broader sense, such as for naming an entire table with their independent rows of a multidimensional (data) matrix or for the whole of " data " in a certain context, ie equivalent to " a set of data", " a collection of data " - for example, all data obtained in a statistical survey, the tax evaders CD etc.

Variations in the storage

Generally corresponds to a record is declared with the expressive means of programming languages ​​, data type, composite or Record, ggf.innerhalb an associative array. The mathematical model of a data set is a tuple.

In detail, data ' but not a technical but a logical term for which there are numerous technical appearance and Implementierungsfomen. For example, can be distinguished records for the following features / properties:

  • Generality: Mandatory defined structures and formats (such as binary data or text, length, other rules ), eg for specific software solutions (like the DTA method ) vs. individually by the user -defined formats.
  • Satz-/Datenfeldlänge: Fixed and uniform length per field vs. variable-length fields, such as with field delimiter as CSV or field length specification; results in fixed or variable length records.
  • Character encoding used: only text characters eg in ASCII code vs. other types of data in a binary code.
  • Field Attributes: Only vs. net data. more information per field ( such as bold, underline, font type, etc., usually not visible).
  • Record limit: end-of- marking vs.. fixed record length.

Also regarding the storage of records can take numerous distinctions. For example:

  • Storage in normal files: here offer alternatives such as: Custom custom data formats and structures,
  • CSV files with semicolon as field separator, etc.,
  • XML format in the form and with other structurally related textually formulated information,
  • RDF format for internet information.
  • In relational databases, records are stored in tabular form, with a record i d corresponds R. a table row.
  • Column -oriented databases do not store all data fields per record after the other, but for each data field, the contents of all the records, one column ( with all its rows) So here stands for ' record '.

For electronic data is considered: they exist in their storage medium as Bit-/Bytefolgen any length. In this data set, the individual data records, and individual data fields are identified by (usually provided by the programming language, and / or system software ) algorithms and addressed and shown for example in rows and columns.

Logical / physical records: several records on electronic storage media are usually grouped into larger storage units. Such units shall be classified differently depending on the computer system, such as, Page '(page, in many database systems ) or as a block ( with conventional storage). In a computer program the processing of each data set are routines upstream (usually the operating system or the DBMS ) that perform the actual reading or writing to disk for optimization reasons block-/seitenweise and position the each individual record in the data block iterative and for processing provide main memory.