注意:
1、 不要过度索引
2、 索引条件列（where后面最频繁的条件列）
3、 尽量索引散列值，过于集中的值不要索引。
索引类型
1、普通索引（index）：仅仅是加快查询速度
2、唯一索引(unique index)：行上的值不能重复
3、主键索引(primary key)：主键不能索引
主键索引必定是唯一的，唯一索引不一定是主键，
一张表上只能一个主键，可以有一个或者多个唯一索引。
4、 全文索引(fulltext index)：在mysql 默认情况下对于中文作用不大。
查看 一张表上的索引
show index from 表名(/G可以横着显示)
索引不知道名称默认以索引的列名作索引
建立索引
alter table 表名add index/unique/fulltext [索引名](列名)
[索引名]可以不写 ，不写默认与列名相同。
alter table 表名add primary key （列名）
创建索引示例：
为 tel列 创建普通索引
全文停止字：
全文索引，不针对非常频繁的词，做索引。
针对汉语意义不大，因为因为英文单词可以依赖空格等标点来判断单词界限，进而对单词进行索引，而中文mysql无法识别单词界限。
以下表列出了默认的全文停止字 ：
a's
able
about
above
according
accordingly
across
actually
after
afterwards
again
against
ain't
all
allow
allows
almost
alone
along
already
also
although
always
am
among
amongst
an
and
another
any
anybody
anyhow
anyone
anything
anyway
anyways
anywhere
apart
appear
appreciate
appropriate
are
aren't
around
as
aside
ask
asking
associated
at
available
away
awfully
be
became
because
become
becomes
becoming
been
before
beforehand
behind
being
believe
below
beside
besides
best
better
between
beyond
both
brief
but
by
c'mon
c's
came
can
can't
cannot
cant
cause
causes
certain
certainly
changes
clearly
co
com
come
comes
concerning
consequently
consider
considering
contain
containing
contains
corresponding
could
couldn't
course
currently
definitely
described
despite
did
didn't
different
do
does
doesn't
doing
don't
done
down
downwards
during
each
edu
eg
eight
either
else
elsewhere
enough
entirely
especially
et
etc
even
ever
every
everybody
everyone
everything
everywhere
ex
exactly
example
except
far
few
fifth
first
five
followed
following
follows
for
former
formerly
forth
four
from
further
furthermore
get
gets
getting
given
gives
go
goes
going
gone
got
gotten
greetings
had
hadn't
happens
hardly
has
hasn't
have
haven't
having
he
he's
hello
help
hence
her
here
here's
hereafter
hereby
herein
hereupon
hers
herself
hi
him
himself
his
hither
hopefully
how
howbeit
however
i'd
i'll
i'm
i've
ie
if
ignored
immediate
in
inasmuch
inc
indeed
indicate
indicated
indicates
inner
insofar
instead
into
inward
is
isn't
it
it'd
it'll
it's
its
itself
just
keep
keeps
kept
know
knows
known
last
lately
later
latter
latterly
least
less
lest
let
let's
like
liked
likely
little
look
looking
looks
ltd
mainly
many
may
maybe
me
mean
meanwhile
merely
might
more
moreover
most
mostly
much
must
my
myself
name
namely
nd
near
nearly
necessary
need
needs
neither
never
nevertheless
new
next
nine
no
nobody
non
none
noone
nor
normally
not
nothing
novel
now
nowhere
obviously
of
off
often
oh
ok
okay
old
on
once
one
ones
only
onto
or
other
others
otherwise
ought
our
ours
ourselves
out
outside
over
overall
own
particular
particularly
per
perhaps
placed
please
plus
possible
presumably
probably
provides
que
quite
qv
rather
rd
re
really
reasonably
regarding
regardless
regards
relatively
respectively
right
said
same
saw
say
saying
says
second
secondly
see
seeing
seem
seemed
seeming
seems
seen
self
selves
sensible
sent
serious
seriously
seven
several
shall
she
should
shouldn't
since
six
so
some
somebody
somehow
someone
something
sometime
sometimes
somewhat
somewhere
soon
sorry
specified
specify
specifying
still
sub
such
sup
sure
t's
take
taken
tell
tends
th
than
thank
thanks
thanx
that
that's
thats
the
their
theirs
them
themselves
then
thence
there
there's
thereafter
thereby
therefore
therein
theres
thereupon
these
they
they'd
they'll
they're
they've
think
third
this
thorough
thoroughly
those
though
three
through
throughout
thru
thus
to
together
too
took
toward
towards
tried
tries
truly
try
trying
twice
two
un
under
unfortunately
unless
unlikely
until
unto
up
upon
us
use
used
useful
uses
using
usually
value
various
very
via
viz
vs
want
wants
was
wasn't
way
we
we'd
we'll
we're
we've
welcome
well
went
were
weren't
what
what's
whatever
when
whence
whenever
where
where's
whereafter
whereas
whereby
wherein
whereupon
wherever
whether
which
while
whither
who
who's
whoever
whole
whom
whose
why
will
willing
wish
with
within
without
won't
wonder
would
would
wouldn't
yes
yet
you
you'd
you'll
you're
you've
your
yours
yourself
yourselves
zero
注意！！换服务器导入数据：
大数据量时，先把索引去掉，导入后，统一加上索引。
索引加快查询速度，降低增删改的速度。
额外：
show create table 表名
可以查看 创建表的语句
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版权声明：本文为CSDN博主「明明如月学长」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/w605283073/article/details/46572555
