Mysql：Changes in MySQL 8.0.17 (2019-07-22, General Availability)：是mysqld 内在转变的版本！！！

Changes in MySQL 8.0.17 (2019-07-22, General Availability)

 

Deprecation and Removal Notes

• FLOAT(M,D) and DOUBLE(M,D) syntax to specify the number of digits for columns of type FLOAT and DOUBLE (and any synonyms) is a nonstandard MySQL extension. This syntax is deprecated and support for it will be removed in a future MySQL version. (Bug #25328973, Bug #84363)

• For string data types, the BINARY attribute is a nonstandard MySQL extension that is shorthand for specifying the binary (_bin) collation of the column character set (or of the table default character set if no column character set is specified). In MySQL 8.0, this nonstandard use of BINARY is ambiguous because the utf8mb4 character set has multiple _bin collations, so the BINARY attribute is deprecated and support for it will be removed in a future MySQL version. Applications should be adjusted to use an explicit _bin collation instead.

  The use of BINARY to specify a data type or character set remains unchanged.

• The nonstandard C-style &&, ||, and ! operators that are synonyms for the standard SQL AND, OR, and NOT operators, respectively, are deprecated and support for them will be removed in a future MySQL version. Applications that use the nonstandard operators should be adjusted to use the standard operators.

  Note

  Use of || is deprecated unless the PIPES_AS_CONCAT SQL mode is enabled. In that case, || signifies the SQL-standard string concatenation operator).

• The ZEROFILL attribute is deprecated for numeric data types, as is the display width attribute for integer data types. Support for ZEROFILL and display widths for integer data types will be removed in a future MySQL version. Consider using an alternative means of producing the effect of these attributes. For example, applications could use the LPAD() function to zero-pad numbers up to the desired width, or they could store the formatted numbers in CHAR columns.

• The UNSIGNED attribute is deprecated for columns of type FLOAT, DOUBLE, and DECIMAL (and any synonyms) and support for it will be removed in a future MySQL version. Consider using a simple CHECK constraint instead for such columns.

• AUTO_INCREMENT support is deprecated for columns of type FLOAT and DOUBLE (and any synonyms) and will be removed in a future MySQL version. Consider removing the AUTO_INCREMENT attribute from such columns, or convert them to an integer type.

• The SQL_CALC_FOUND_ROWS query modifier and accompanying FOUND_ROWS() function are now deprecated and will be removed in a future MySQL version. As a replacement, considering executing your query with LIMIT, and then a second query with COUNT(*) and without LIMIT to determine whether there are additional rows. For example, instead of these queries:

  SELECT SQL_CALC_FOUND_ROWS * FROM tbl_name WHERE id > 100 LIMIT 10;
  SELECT FOUND_ROWS();
  

  Use these queries instead:

  SELECT * FROM tbl_name WHERE id > 100 LIMIT 10;
  SELECT COUNT(*) WHERE id > 100;
  

  COUNT(*) is subject to certain optimizations. SQL_CALC_FOUND_ROWS causes some optimizations to be disabled.