- #Sqlite regex how to
- #Sqlite regex code
#Sqlite regex code
ORDER BY LENGTH( name) DESC Code language: SQL (Structured Query Language) ( sql ) It sorts the track names by their lengths: SELECT Name FROM The following statement returns all track names from the tracks table in the sample database. SELECT substr( 'SQLite substr', 8) Code language: SQL (Structured Query Language) ( sql ) substr('SQLite substr', 8)
#Sqlite regex how to
The following statement demonstrates how to use the substr function with only the first two arguments, the length argument is omitted. SQLite Code language: SQL (Structured Query Language) ( sql ) SELECT substr( 'SQLite substr', 7, -6) Code language: SQL (Structured Query Language) ( sql ) substr('SQLite substr', 7, -6) The following statement illustrates how to use the substr() function with a negative length argument. Substr Code language: SQL (Structured Query Language) ( sql ) SELECT substr( 'SQLite substr', - 6, 6) Code language: SQL (Structured Query Language) ( sql ) substr('SQLite substr', -6, 6) The following statement returns a substring from a string using a negative start argument.
The following statement extracts and returns a substring from the SQLite substr string: SELECT substr( 'SQLite substr', 1, 6) Code language: SQL (Structured Query Language) ( sql ) substr('SQLite substr', 1, 6) If any argument is NULL, the substr() function will return NULL. If it is omitted, it is assumed to be the maximum positive integer. The length argument determines the length of the substring. The length argument is optional. See the following picture of a sample string with the positive and negative start
If the start is a negative integer, the returned substring consists of the length number of character starting from the end of the string. If the start is a positive integer, the substr() function returns a substring starting from the beginning of the string. The start argument can be a positive or negative integer The start argument is an integer that specifies the starting position of the returned substring. The string to be used to extract the substring. The substr() function accepts three arguments. The starting position of the substring is determined by the start argument and its length is determined by the length argument. Syntax substr( string, start, length ) Code language: SQL (Structured Query Language) ( sql ) Selecting redundant columns may result in unnecessary performance degradation.The SQLite substr function returns a substring from a string starting at a specified position with a predefined length. Avoid Selecting Unnecessary Columns (query line: 2): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Consider replacing this call with an alternative condition that won’t use a regular expression. Avoid Regular Expression Filtering (query line: 29): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index. 
Avoid Regular Expression Filtering (query line: 26): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index. Avoid Regular Expression Filtering (query line: 23): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index. Avoid Regular Expression Filtering (query line: 16): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index. Avoid Regular Expression Filtering (query line: 13): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index. 
Avoid Regular Expression Filtering (query line: 10): When a regular expression filtering is applied on an indexed column, the database's optimizer won’t be able to use the index.The optimization process and recommendations:
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