今晚有时间，整理了一下Transact-SQL的一些内容，顺便也复习了一下。
有些函数是经常用的。有些哦还没用过
没有校对，可能有错误的地方

集合函数

avg([all|distinct]expression)
count(*)
count([all|distinct]expression)
max(expression)
min(expression)
sum([all|distinct]expression)

数据类型转换函数
convert(datatype|(length)|(precision[,scale])|,expression[,style])
hextoint(hexadecimal_string)
inttohex(integer_expression)

日期函数
dateadd(datepart,numeric_expression,date)
datediff(datepart,date1,date2)
datename(datepart,date)
getdate()

数字函数
abs(numeric)
acos(approx_numeric)
asin(approx_numeric)
atan(approx_numeric)
atn2(approx_numeric1,approx_numeric2)
ceiling(numeric)
cos(approx_numeric)
cot(approx_numeric)
degrees(numeric)
exp(approx_numeric)
floor(numeric)
log(approx_numeric)
log10(approx_numeric)
pi()
power(numeric,power)
radians(numeric)
rand([integer])
round(numeric,integer)
sign(numeric)
sin(approx_numeric)
sqrt(approx_numeric)
tan(approx_numeric)

字符串函数
ascii(char_expr)
char(integer_expr)
charindex(expression1,expression2)
char_length(char_expr)
difference(char_expr1,char_expr2)
lower(char_expr)
ltrim(char_expr)
patindex("%pattern%",char_expr[,using{bytes|chars|characters}])
replicate(cahr_expr,integer_expr)
reverse(char_expr)
right(char_expr,interger_expr)
rtrim(char_expr)
soundex(char_expr)
space(inter_expr)
str(approx_numeric[,length[,decimal]])
stuff(char_expr1,start,length)
upper(char_expr)

系统函数
col_name(object_id,column_id[,database_id])
col_length(object_name,column_name)
curunreservedpgs(dbid,lstart,unreservedpgs)
data_pgs(object_id,{doampg|ioampg})
datalength(expression)
db_id([database_name])
db_name([database_id])
host_id()
host_name()
index_col(object_name,index_id，key_#[,user_id])
isnull(expression1,expression2)
lct_admin({{"lastchance"|"logfull"|"unsuspend"},database_id}|"reserve",log_page})
object_id(object_name)
object_name(object_id{,database_id})
proc_role("sa_role"|"sso_role"|"oper_role")
reserved_pge(object_id,{doampg|ioampg})
rowcnt(doampg)
show_role()
suer_id([server_user_name]）
suer_name([server_user_id])
tsequal(timestamp,timestamp2)
used_pgs(object_id,doampg,ioampg)
user
user_id([user_name])
user_name([user_id])
valid_name(character_expression)
valid_user(server_user_id)

text and image函数
patindex("%pattern%",char_expr[,using{bytes|chars|character}]）
textptr(text_columname)
textvalid("table_name.col_name",textpointer)