CREATE TABLE t1 ( c1 char(10) NOT NULL PRIMARY KEY, c2 int, c3 char(10), c4 char(10) NOT NULL, CONSTRAINT c4 UNIQUE (c1,c4) ) CREATE INDEX Index1 ON t1 (c2 ASC)请问，执行上面语句后，表t1上有多少个索引？
显示全部CREATE TABLE t1
(
c1 char(10) NOT NULL PRIMARY KEY,
c2 int,
c3 char(10),
c4 char(10) NOT NULL,
CONSTRAINT c4 UNIQUE (c1,c4)
)
CREATE INDEX Index1 ON t1 (c2 ASC)
请问，执行上面语句后，表t1上有多少个索引？
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