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Hash structure
An indexing method used to find quickly the data of a base table that matches a search condition. A hash structure is a
storage structure that makes fast data manipulation possible as follows. A hash structure uses a has function to
determine the storage location of data using the value of a data key. SymfoWARE/RDB uses this mechanism in
RANDOM structures that are the storage structures for base tables.
Related terms:
B-tree structure, RANDOM structure
Host variable
A variable for passing data between an application program and a database in SQL statements that manipulate data.
Index
Key data for increasing the efficiency of retrieving table data. If efficient data retrieval is not possible in
SymfoWARE/RDB using only the primary key specified in the table definition, a supplemental positional key data can
be created. This key data is called an index. An index can be created for each column of a table or for several
combined columns. An index is established in a storage structure definition.
Index definition
A definition that indicates the columns of a table for which the index is created. To increase data manipulation
efficiency, an index is required for frequently searched columns.
Index part
A constituent element of a storage structure. The index part is the portion that stores the data of an index for retrieving
data stored in the data part. The index part is a constituent element of a BTREE structure.
Related terms:
Data part
Indicator variable
In high-level languages such as C language and COBOL, the indicator variable is a variable specified to be paired
with an SQL data variable. Indicator variables are used when SQL statements are used to fetch data from, and update
a data base. When SQL statements are used to update a data base, the indicator variable indicates whether or not
data stored in the SQL data variable contains a null value. When SQL statements are used to reference a data base,
the indicator variable indicates whether or not the execution result of the SQL statement has a null value stored in the
SQL data variable. The indicator variable also shows the number of characters in character-string data stored in the
SQL data variable.
INSERT statement
The INSERT statement is an SQL data manipulation statement used to add rows to a table.
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