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Databases & SQL vocabulary · Data Modeling and Normalization

ER diagram

Meaning in databases & SQL, with examples

nounCore term

In databases & SQL, ER diagram means: A drawing of a database design that shows the entities (usually tables), their attributes and the relationships between them, such as one-to-many.

In Turkish: varlık-ilişki diyagramı, ER diyagramı

How it is used

ER stands for entity-relationship; the short form ERD is also common. Teams draw ER diagrams before building a schema and generate them from existing databases for documentation. Lines often use crow's foot notation to show 'one' and 'many'.

Example sentences

  1. Let's sketch an ER diagram before we create any tables.

  2. The ER diagram in the wiki is two years old and missing half the tables.

Common collocations

  • draw an ER diagram
  • ERD
  • entity-relationship model
  • crow's foot notation
  • one-to-many relationshipA link between two tables where one row in the first table can be connected to many rows in the second, but each of those belongs to only one, like a customer and their orders.
  • many-to-many relationshipA link where many rows in one table can relate to many rows in another, like students and courses. It needs a third table in between to store the pairs.
  • schemaThe structure of a database: its tables, columns, data types, keys and relationships. In some products it is also a named group of tables inside a database.
  • cardinalityEither the type of relationship between tables (one-to-one, one-to-many, many-to-many) or the number of distinct values in a column.
  • normalizationThe process of organizing tables so that each fact is stored in only one place, which reduces repeated data and prevents update mistakes.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Data Modeling and Normalization

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