Procedures for intercepting string functions in MySQL

How does MySQL intercept string functions ?? Function: 1. Extract the string left (str, length) from the left. Description: left (truncated field, truncated length) Example: selectleft (content, 200) asabstractfrommy_content_t2. The right (str, length) string is truncated from the right. Description: rig

How does MySQL intercept string functions ?? Function: 1. Extract string left (str, length) from left. Description: left (truncated field, truncated length) Example: select left (content, 200) as abstract from my_content_t 2. Extract the right (str, length) string from the right. Description: rig

MySQL string truncation Function Method

MySQL string truncation Function Method

?? Function:

1. Extract strings from the left

Left (str, length)

Note: left (truncated field, truncated length)

Example: select left (content, 200) as abstract from my_content_t

2. Extract strings from the right

Right (str, length)

Note: right (intercepted field, truncated length)

Example: select right (content, 200) as abstract from my_content_t

3. truncate a string

Substring (str, pos)

Substring (str, pos, length)

Description: substring (truncated field, starting from the nth digit)

Substring (truncated field, starting from the nth digit and intercepting the length)

Example: select substring (content, 5) as abstract from my_content_t

Select substring (content, 5,200) as abstract from my_content_t

(Note: if the number of digits is negative, for example,-5, it is the length from the last to the end or truncation of the string)

4. truncate a string by keyword

Substring_index (str, delim, count)

Note: substring_index (intercepted field, keyword, number of times the keyword appears)

Example: select substring_index ("blog.chinabyte.com ",".", 2) as abstract from my_content_t

Result: blog. chinabyte

(Note: if the number of times a keyword appears is negative, for example,-2, it is counted from the last to the end of the string)

Result: chinabyte.com