MySQL參考手冊版本：refman-5.6-en.a4.pdf
下載地址：http://dev.mysql.com/doc/index-archive.html
- Options on the command line take precedence over values specified in option files and environmentvariables, and values in option files take precedence over values in environment variables. [2.12]
- On character type columns, sorting—like all other comparison operations—is normally performed in a case-insensitive fashion.This means that the order is undefined for columns that are identical except for their case. You can force a case-sensitive sort for a column by using BINARY like so: ORDER BY BINARY col_name. [3.3.4.4]
簡譯：對于字符型列來說摘投，排序是不區(qū)分大小寫的。如果想讓字符型列排序區(qū)分大小寫可以使用BINARY，如：ORDER BY BINARY col_name - TIMESTAMPDIFF(YEAR,birth,CURDATE()) as age =》計算年齡
- MONTH(birth) = MOD(MONTH(CURDATE()), 12) + 1;=》選擇得到生日在下個月窒篱。MOD()進行取模運算[3.3.4.6]
- You cannot use arithmetic comparison operators such as =, <, or <> to test for NULL. [3.3.4.6] =>計算符號對NULL是沒有任何意義的
- In MySQL, 0 or NULL means false and anything else means true. The default truth value from a boolean operation is 1. =》在MySQL中，0或者NULL都是false的意思，其他的則為true阱州。從bool運算中得到true值是用1表示
- Two NULL values are regarded as equal in a GROUP BY.
- When doing an ORDER BY, NULL values are presented first if you do ORDER BY ... ASC and last if you do ORDER BY ... DESC.
- 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. =》使用NULL一個常見的錯誤就是以為對聲明為NOT NULL的列不能插入0或者空字符串，其實是可以的法梯。
- SQL pattern matching enables you to use “_” to match any single character and “%” to match an arbitrary number of characters (including zero characters).=>SQL正則表達式允許使用"_"來匹配任意單個字符,使用“%”來匹配任意個數(shù)字符苔货，包括0個石挂。[3.3.4.7]
- In MySQL, SQL patterns are caseinsensitive by default.=》MySQL中正則表達式對大小寫并不敏感救军。
- SELECT * FROM pet WHERE name REGEXP '^b';
- If you really want to force a REGEXP comparison to be case sensitive, use the BINARY keyword to make one of the strings a binary string.SELECT * FROM pet WHERE name REGEXP BINARY '^b';
- If you want to get the interactive output format in batch mode, use mysql -t. To echo to the output the statements that are executed, use mysql -v. =》如果想在批處理模式也就是source file這種模式下的輸出和登錄MySQL的輸出一樣是表狀的，那么就是用mysql -t選項啸胧。如果你想同時在輸出時同時打印執(zhí)行的sql铛绰，使用-v選項诈茧。
- MySQL does not perform any sort of CHECK to make sure that col_name actually exists in tbl_name (or even that tbl_name itself exists).[3.6.6]=>MySQL的references tbl_name(col_name)語法不會做任何col_name是否存在的檢查，即使tal_name是存在的捂掰。這里只是說references這個語法敢会，并不是說創(chuàng)建外鍵時不檢查目標表和目標列的存在.
- When you insert any other value into an AUTO_INCREMENT column, the column is set to that value and the sequence is reset so that the next automatically generated value follows sequentially from the largest column value.
- For a multiple-row insert, LAST_INSERT_ID() and mysql_insert_id() actually return the AUTO_INCREMENT key from the first of the inserted rows.
- --column-names option that determines whether or not to display a row of columnnames at the beginning of query results. [4.2.5 ] =>這樣子來說的話，--column-names這個參數(shù)在用來執(zhí)行select一個表數(shù)據(jù)時還是蠻好用的这嚣。因為默認是會把列名一起導出來的
#enalbled
--disable-column-names
--skip-column-names
--column-names=0
#disabled
--column-names
--enable-column-names
--column-names=1
- A MySQL program started with the --no-defaults option reads no optionfiles other than .mylogin.cnf [4.2.6 ]
-
!includedirectives in option files to include other option files and!includedirto search specific directories for option files. **Any files to be found and included using the!includedirdirective on Unixoperating systems must have file names ending in .cnf. **
!include /home/mydir/myopt.cnf
!includedir /home/mydir
