| 241 |
Base tables with multiple name columns |
Find base tables with more than one name columns. Perhaps the normalization level of the table is low. |
General |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |
| 242 |
Base tables that have no uniqueness requirement for rows whatsoever |
Find base tables without any unique constraints and primary key as well as any unique index, whether it is created explicitly by a developer or automatically by the DBMS. The only legitimate reason of such a table is if it is an abstract table that is used to define common columns of subtables. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 243 |
Base tables that have neither a unique constraint nor the primary key |
Find base tables without any unique constraints and the primary key. In such tables there are no restrictions for recording duplicate rows. Each row represents a true proposition about the real world. It does not make the proposition truer if one presents it more than once. Moreover, duplicate rows increase data size. Without keys the DBMS lacks vital information about data in the database that it can internally use to choose better execution plans and in this way improve performance of database operations. The only legitimate reason of such a table is if it is an abstract table that is used to define common columns of subtables. |
Problem detection |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |
| 244 |
Perhaps incorrect use of 'NULL' |
Find Boolean expressions, queries, routines, and default values that refer to value 'NULL'. Perhaps NULL was intended instead. 'NULL' is a string (a value) but NULL is a special marker for denoting missing value. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 245 |
Too generic names (candidate key columns) |
Find candidate key columns with the names like id, identifikaator, code, kood, number, etc. The names should have a prefix or a suffix. These are too generic names. |
Problem detection |
system catalog base tables only |
2025-11-07 10:11 |
MIT License |
View |
| 246 |
Do not clone tables |
Find cases where a base table has been split horizontally into multiple smaller base tables based on the distinct values in one of the columns of the original table. Each such newly created table has the name, a part of which is a data value from the original tables. Find base tables that have the same columns (column name, column order, data type) and the difference between the tables are the numbers in the table names (table1, table2, etc.). |
Problem detection |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |
| 247 |
Unique index definition instead of a key declaration |
Find cases where a unique constraint (that is not case-insensitive or partial, i.e., applies only to certain rows) has been enforced by using a CREATE UNIQUE INDEX statement instead declaring a PRIMARY KEY, UNIQUE, or EXCLUDE constraint. You should try to work on as high level of abstraction as possible. According to the ANSI-SPARC Architecture indexes are a part of internal database schema whereas constraints are a part of conceptual schema, i.e., at the higher level of abstraction. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 248 |
Mixing Concat and || |
Find cases where different means are used to concatenate text within the same object. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 249 |
Mixing Concat and Coalesce |
Find cases where different means are used to deal with NULLs in case of concatenating texsts. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 250 |
Perhaps CHECK should be associated with a domain |
Find cases where multiple columns with the same domain have exactly the same CHECK constraint that is directly associated with the table. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 251 |
Multiple tables share the same state classifier |
Find cases where multiple tables share the same state classifier. For each main entity type one should create a separate state classifier table. Even if the classifier values are the same in case of two entity types for now these may become different in the future. Having a shared state classifier table usually means very simplistic state machines (states active and inactive) that could point to the gaps in analysis. |
Problem detection |
system catalog base tables only |
2025-11-07 10:11 |
MIT License |
View |
| 252 |
Optional columns before mandatory columns |
Find cases where optional columns are before a mandatory column. Place mandatory columns before optional columns to improve comprehensibility of the table. |
Problem detection |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |
| 253 |
Some CHECKS are associated with a domain and some with the base table columns that have the domain |
Find cases where some CHECKS are associated with a domain and some with the base table columns that have the domain. Avoid duplication of code. Write as little code as possible. If possible, move things "before the brackets" so to say. In this case it means declaring CHECKS at the level of the domain and not at the level of base table columns. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 254 |
Sometimes CHECK, sometimes not |
Find cases where the column with the same name in different tables sometimes has a check constraint and sometimes not. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 255 |
Function in a function-based index of a column is different from the function that is used in the subquery of a derived table |
Find cases where the function of a function-based index of a column is different from the function that is used in the query in a derived table based on the column. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 256 |
Do not specify a list of values in a table column definition |
Find cases where the list of valid data values in the column is specified in the column definition (in addition to specifying the type of the column) by using, for instance, check constraints or enumerated types. The check constraint is either associated directly with a table or is associated with a domain. |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 257 |
Do not use dual-purpose foreign keys |
Find cases where the same column of a base table T is used to record references to multiple base tables. In addition, one has to add additional column to T for holding metadata about the parent table, referenced by the current row. |
Problem detection |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |
| 258 |
Duplicate triggers |
Find cases where the same table has multiple triggers with the same type (row-level, statement-level) that react to the same event with the same WHEN condition and with the same way (by invoking the same function). |
Problem detection |
INFORMATION_SCHEMA+system catalog base tables |
2025-11-07 10:11 |
MIT License |
View |
| 259 |
Short cycle (columns) |
Find cases where two candidate keys of the same table that are also foreign keys reference to each other. |
Problem detection |
system catalog base tables only |
2025-11-07 10:11 |
MIT License |
View |
| 260 |
Do not assume you must use files |
Find cases where you store images and other media as files outside the database and store in the database only paths to the files. |
Problem detection |
INFORMATION_SCHEMA only |
2025-11-07 10:11 |
MIT License |
View |