Database Reference
In-Depth Information
LJQ rightRows denotes a set of rows of the right table. LJQ set denotes a set which consist of
two elements. The
rst element is the LJQ rightRows , and the second element is the
LJQ leftRows . LJQ rows denotes a set of rows for a left CTT and right CTT. LJQ array denotes
a two dimensional array that stores the retrieved rows.
5.5 Targeted Tables Query Algorithm
This algorithm combines the result-set of two, or more tables, whether they are CTTs,
VETs or a combination of both types of tables. It uses query
lters on multiple tables or
ltering of data based on the results of subqueries. These complex queries can be
executed by calling the function that executes this algorithm. Figure 5 shows an example
of a set of tables that have relationships between them. Table A (Root Table) and table C
have a Many-to-Many database relationship, while table B is a join table that construct
the relationship. Table C and table D have a One-to-Many relationship. Finally, Table D
and table E (Targeted Table) have a One-to-Many relationship. This algorithm
lters the
data in the Targeted Table E based on a number of query results obtained from table A to
table D.
Root Table
A
C
B
D
Targeted Table
E
Fig. 5.
Targeted Tables example
Denition 8 (Targeted Tables Query Algorithm). TTQ tables denotes a set of CTTs
and/or VETs names. TTQ tablesSize denotes the size of TTQ tables . TTQ PK denotes a set of
row matrix with 2 rows and n columns. The
rst row stores the column name of a table
primary key. The second row stores the value of a table primary key. TTQ select denotes
a set of SELECT clauses, where each table in TTQ tables may have a SELECT clause.
TTQ where denotes a set of WHERE clauses, where each table in TTQ tables may have
a SELECT clause. TTQ type denotes a table type of a table in TTQ tables . TTQ tablesi denotes
a current root table. TTQ tablesiĆ¾ 1 denotes a current targeted table. Figure 6 shows an
example of current root table and current targeted table that this algorithm may reaches
during iterating the targeted table sequence list. TTQ relation denotes a relationship
between two tables. TTQ PKi denotes a primary key set for a current root table in
the TTQ tables . This set has only primary key IDs without values that can be obtained
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