Pronunciation: [ˌiːkwɪd͡ʒˈɔ͡ɪn] (IPA) 
Equijoin is a term used in database theory to describe a specific type of join operation. The word is spelled with three syllables: e-kwuh-join. The first syllable is pronounced with a short "e" sound as in "bet." The second syllable is pronounced "kwuh," with the "w" sound connecting the "k" and "u" sounds. The final syllable is pronounced "join" as in "together." The IPA phonetic transcription for equijoin is /ˈɛkwədʒɔɪn/.
Equijoin is a term used in relational databases to describe a type of join operation that combines two tables based on the equality of corresponding values in a specified column or set of columns. It is a specific type of join that performs comparisons using the equality operator (=).
An equijoin is performed by comparing each value in the specified column(s) of one table with the corresponding value(s) in the column(s) of the other table. When the values match, the rows from both tables are combined into a result set. The result set only includes the rows where the values are equal in both tables.
Equijoins are commonly used when you want to combine data from two tables that have a related or matching attribute. For example, if you have a "Customers" table and an "Orders" table, and you want to retrieve all the orders made by customers with a specific ID, you would perform an equijoin using the "customer_id" column as the matching attribute. This would result in a new table that contains only the rows where the customer IDs match in both tables.
Equijoins can be further classified into inner equijoins, which return only the matching rows, and outer equijoins, which also include non-matching rows from one or both tables. Inner equijoins are the most common type of equijoin used in database operations.
In summary, an equijoin is a join operation in relational databases that combines two tables based on the equality of specific column(s), resulting in a new table containing only the matching rows.
The word "equijoin" is a blend of two terms: "equi" and "join".
- "Equi" comes from the Latin word "aequus", meaning equal or same. In the context of databases, it refers to the condition of two or more values being equal.
- "Join" comes from the English word which means to combine or merge.
Therefore, "equijoin" in the context of databases refers to the operation of combining two tables based on the equality of certain columns or attributes.
