JPH0498544A - Data limit control system - Google Patents

Abstract

PURPOSE:To improve the retrieving performance for limit of the NULL value by providing a NULL value limit analyzing means, a non-NULL value information generating means, and a non-NULL value information storing means. CONSTITUTION:A non-NULL value information storing means 1 stores the non-NULL value information produced by a non-NULL value information gener ating means 3 into a definition information storing device 2 so that the non- NULL value information can be recognized for each table definition. A column is retrieved out of the table definition with input of a data defining language and the column No is stored if the NULL value is limited in the column. Then the column No added with the limit of the NULL value that is analyzed by a NULL value limit analyzing means 4 is retrieved. The the bit corresponding to the column No of the non-NULL value information is turned on with a column No added with the limit of the NULL value and then turned off with a column No containing no limit added to the NULL value. Thus the unitary control is attained to the presence or absence of the limit given to the NULL value contained in the table definition.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides an information processing system in which the minimum unit of data input by a user is a column and a collection of unordered rows is provided to the user as a table. , relates to a non-NULL value constraint determination method in a database system in which NULL values can be specified.

[Conventional technology] Conventionally, database technology in information processing systems
In a database system where the minimum unit of data input by a user is a column, a collection of unordered rows is a table, and NULL values are allowed in the data input by the user, non-NULL value information does not exist, and columns When data input occurs, NU is added to the column information.
Whether or not an LL value constraint has been added is determined by searching the definition information storage device each time for column information in the related table definition information.

[Problems to be Solved by the Invention] Conventionally, in data hashing technology in information processing systems, column information in related table definition information is used to determine whether or not a NULL value constraint is added to a column in which data is to be input. Searches and judgments were conducted each time.

Therefore, when a NULL value is input during data input, a search is performed regardless of whether or not column information has a NULL value constraint, which poses a problem in improving processing efficiency.

The present invention provides non-NULL (NU by setting i information)
It is expected that the search process for LL value constraints will be improved.

[Means for solving the problem] In a database system where the minimum unit of data input by the user is a column, a collection of unordered rows is a table, and NULL values are allowed in the data input by the user, A NULL value constraint that analyzes the data definition language created by the user and analyzes whether the user has specified in advance that NULL values are not allowed in the data input to the column when generating table definition information. an analysis means; a non-NULL value information generating means for creating non-NULL information for recognizing for which column in related table definition information a NULL value constraint is specified; Non-NULL value information created by the information generating means is stored on the table definition information side in the definition information storage device.
It has a ULL value information storage means, and when data is input to a certain column, it exists in one table without having to refer to the column information in the related table definition information in the definition information storage device each time. A data constraint management information method that can determine whether a NULL value constraint exists for a column all at once.

Next, the present invention will be explained in detail with reference to the drawings. NULL value analysis means 4 that analyzes whether a NULL value constraint is specified in column information when creating information; manages which column in one table definition has a NULL value constraint specified or not; Non-NULL that generates non-NULL information
Value information generation means 3, non-NULL value information that stores the non-NULL value information generated by the non-NULL value information generation means 3 so that it can be recognized for each table definition.
It is stored in the definition information storage device 2 by the value information storage means 1.

The details of the operation of the NULL value constraint analysis means and the non-NULL value information generation means will be explained below with reference to the drawings.

(2) Non-NULL value constraint information generation means FIG. 2 is a flowchart showing the processing flow of the NULL value constraint analysis means.

Referring to Figure 2, data definition language input (step 2)
01), searches for columns that exist in the table definition,
If a column has a NULL value constraint, its column number is memorized (step 203). This process is repeated until the column continues to exist (step 204).

(3) Search for the column number to which the non-NULL value information generation means 1 and the NULL value constraint analysis means have analyzed and added the NULL value constraint (Step 301)
, non-NULL if the column number has a NULL value constraint
Turn on the bit corresponding to the column number of value information Step 30
2) If the column number does not have an NLILL value constraint attached, the via-to is turned off (step 303). Processing continues until the column number equals the total number of columns present in the table definition (step 304).

Next, the general processing flow will be explained using a specific example.

As shown in FIG. 5, when a data definition language 401 is available, a column with a NULL value constraint is searched and the column number of the added column is stored in a temporary storage area 402.

Next, non-NULL value information 502 is created based on the stored column number 501 as shown in FIG.

[Effects of the Invention] As explained above, the present invention analyzes the NULL value constraints specified in a column when inputting a data definition language, and creates non-NULL value information, thereby unifying the presence or absence of NULL value constraints in a table definition. can be managed effectively.

Therefore, if an input occurs in a column, NrJLL
Value constraints can be searched immediately and processing efficiency is achieved. FIG. 1 is a diagram showing an embodiment of the present invention.

1... Non-NULL value information storage means, 2... Definition information storage device, 3... Non-NLILL value information generation means, 4.
. . . NULL value constraint analysis means, 5 . . . processing start instructing device FIG. 2 is a diagram showing analysis processing of NULL value constraints.

FIG. 3 is a diagram showing non-NULL value information generation processing.

4 and 5 are state models that generate non-NULL value information.

Claims (1)

[Claims] The minimum unit of data input by the user is a column, a collection of unordered rows is a table, and data with undefined values (hereinafter referred to as NULL values) in the data input by the user is defined as a column. In permitted database systems, when a data definition language created by a user is analyzed and table definition information is generated, data entered by the user for a column must contain NUL.
A NULL value constraint analysis means for analyzing whether it has been specified in advance that L values are not allowed, and a method for recognizing which column in the related table definition information the NULL value constraint is specified for. non-NULL value information generation means for creating non-NULL value information of the non-NULL value information;
It has a ULL value information storage means, and when data is input to a certain column, it exists in one table without having to refer to the column information in the related table definition information in the definition information storage device each time. NUL for columns all at once
A data constraint management information method characterized by being able to determine whether an L value constraint exists.