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https://dev.mysql.com/doc/refman/5.7/en/partitioning-handling-nulls.html
Partitioning in MySQL does nothing to disallow NULL as the value of a partitioning expression, whether it is a column value or the value of a user-supplied expression. Even though it is permitted to use NULL as the value of an expression that must ...We can verify this behavior by examining the effects on the file system of creating a table partitioned by HASH and populating it with a record containing appropriate ...
https://dev.mysql.com/doc/refman/5.7/en/working-with-null.html
A common error when working with NULL is to assume that it is not possible to insert a zero or an empty string into a column defined as NOT NULL, but this is not the case. The NULL value can be surprising until you get used to it. Conceptually, ...
https://dev.mysql.com/doc/refman/5.7/en/string-functions.html
mysql> SELECT CONCAT_WS(',', 'First name', 'Second name', 'Last Name'); -> 'First name,Second name,Last Name' mysql> SELECT CONCAT_WS(',', 'First name', NULL, 'Last Name'); -> 'First name,Last Name' CONCAT_WS() does not skip empty strings. The ...
https://dev.mysql.com/doc/refman/5.7/en/problems-with-null.html
The concept of the NULL value is a common source of confusion for newcomers to SQL, who often think that NULL is the same thing as an empty string ''. For example, the following statements are completely different: mysql> INSERT INTO my_table ...In ...When reading data with LOAD DATA, empty or missing columns are updated with ...
https://dev.mysql.com/doc/refman/5.7/en/is-null-optimization.html
MySQL can perform the same optimization on col_name IS NULL that it can use for col_name = constant_value. For example, MySQL can use indexes and ranges to search for NULL with IS NULL. This optimization does not occur in cases when the column ...
https://dev.mysql.com/doc/refman/5.7/en/null-values.html
Be aware that the NULL value is different from values such as 0 for numeric types or the empty string for string types. The NULL value means “no data.” NULL can be written in any lettercase. Treatment of \N as a synonym for NULL in SQL ...For ...
https://dev.mysql.com/doc/refman/5.7/en/load-data.html
\Z ASCII 26 (Control+Z) \N NULL For more information about \-escape syntax, see Section 9.1.1, “String Literals”. This differs from the word NULL enclosed within FIELDS ENCLOSED BY characters, which is read as the string 'NULL'. With fixed-row ...Input File Character Set The file name must be given as a literal ...The file can be read from the server ...
https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html
secure_file_priv Command-Line Format --secure-file-priv=dir_name System Variable secure_file_priv Scope Global Dynamic No Type String Default Value platform specific Valid Values empty stringdirnameNULL This variable is used to limit the effect of ...A client that authenticates using the InitSecurityContext() function should provide a string identifying the service to which it connects ...
https://dev.mysql.com/doc/refman/5.7/en/string-comparison-functions.html
Table 12.13 String Comparison Functions and Operators Name Description LIKE Simple pattern matching NOT LIKE Negation of simple pattern matching STRCMP() Compare two strings If a string function is given a binary string as an argument, the ...For ...
https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html
Table 12.4 Comparison Operators Name Description > Greater than operator >= Greater than or equal operator < Less than operator <>, != Not equal operator <= Less than or equal operator <=> NULL-safe equal to operator = Equal operator BETWEEN ...