IN同类的函数INSTR, FIND_IN_SET还有 LIKE , REGEXP但效率上都差不了多少，具体要你的语句。
expr IN (value,...) Returns 1 if expr is equal to any of the values in the IN list, else returns 0. If all values are constants, they are evaluated according to the type of expr and sorted. The search for the item then is done using a binary search. This means IN is very quick if the IN value list consists entirely of constants. Otherwise, type conversion takes place according to the rules described in Section 11.2.2, “Type Conversion in Expression Evaluation”, but applied to all the arguments. mysql> SELECT 2 IN (0,3,5,7); -> 0 mysql> SELECT 'wefwf' IN ('wee','wefwf','weg'); -> 1You should never mix quoted and unquoted values in an IN list because the comparison rules for quoted values (such as strings) and unquoted values (such as numbers) differ. Mixing types may therefore lead to inconsistent results. For example, do not write an IN expression like this: SELECT val1 FROM tbl1 WHERE val1 IN (1,2,'a');Instead, write it like this: SELECT val1 FROM tbl1 WHERE val1 IN ('1','2','a');The number of values in the IN list is only limited by the max_allowed_packet value. To comply with the SQL standard, IN returns NULL not only if the expression on the left hand side is NULL, but also if no match is found in the list and one of the expressions in the list is NULL.
主要受SQL语句的长度限制。
-> 0
mysql> SELECT 'wefwf' IN ('wee','wefwf','weg');
-> 1You should never mix quoted and unquoted values in an IN list because the comparison rules for quoted values (such as strings) and unquoted values (such as numbers) differ. Mixing types may therefore lead to inconsistent results. For example, do not write an IN expression like this: SELECT val1 FROM tbl1 WHERE val1 IN (1,2,'a');Instead, write it like this: SELECT val1 FROM tbl1 WHERE val1 IN ('1','2','a');The number of values in the IN list is only limited by the max_allowed_packet value. To comply with the SQL standard, IN returns NULL not only if the expression on the left hand side is NULL, but also if no match is found in the list and one of the expressions in the list is NULL.
3,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,
50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76
,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,10
2,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,12
2,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,14
2,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,16
2,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,18
2,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,20
2,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,22
2,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,24
2,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,26
2,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,28
2,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,30
2,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,32
2,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,34
2,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,36
2,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,38
2,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,40
2,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,42
2,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,44
2,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,46
2,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,48
2,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,50
2,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,52
2,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,54
2,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,56
2,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,58
2,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600,601,60
2,603,604,605,606,607,608,609,610,611,612,613,614,615,616,617,618,619,620,621,62
2,623,624,625,626,627,628,629,630,631,632,633,634,635,636,637,638,639,640,641,64
2,643,644,645,646,647,648,649,650,651,652,653,654,655,656,657,658,659,660,661,66
2,663,664,665,666,667,668,669,670,671,672,673,674,675,676,677,678,679,680,681,68
2,683,684,685,686,687,688,689,690,691,692,693,694,695,696,697,698,699,700,701,70
2,703,704,705,706,707,708,709,710,711,712,713,714,715,716,717,718,719,720,721,72
2,723,724,725,726,727,728,729,730,731,732,733,734,735,736,737,738,739,740,741,74
2,743,744,745,746,747,748,749,750,751,752,753,754,755,756,757,758,759,760,761,76
2,763,764,765,766,767,768,769,770,771,772,773,774,775,776,777,778,779,780,781,78
2,783,784,785,786,787,788,789,790,791,792,793,794,795,796,797,798,799,800,801,80
2,803,804,805,806,807,808,809,810,811,812,813,814,815,816,817,818,819,820,821,82
2,823,824,825,826,827,828,829,830,831,832,833,834,835,836,837,838,839,840,841,84
2,843,844,845,846,847,848,849,850,851,852,853,854,855,856,857,858,859,860,861,86
2,863,864,865,866,867,868,869,870,871,872,873,874,875,876,877,878,879,880,881,88
2,883,884,885,886,887,888,889,890,891,892,893,894,895,896,897,898,899,900,901,90
2,903,904,905,906,907,908,909,910,911,912,913,914,915,916,917,918,919,920,921,92
2,923,924,925,926,927,928,929,930,931,932,933,934,935,936,937,938,939,940,941,94
2,943,944,945,946,947,948,949,950,951,952,953,954,955,956,957,958,959,960,961,96
2,963,964,965,966,967,968,969,970,971,972,973,974,975,976,977,978,979,980,981,98
2,983,984,985,986,987,988,989,990,991,992,993,994,995,996,997,998,999,1000,1001,
1002,1003,1004,1005,1006,1007,1008,1009,1010,1011,1012,1013,1014,1015,1016,1017,
1018,1019,1020,1021,1022,1023,1024,1025,1026,1027,1028,1029,1030,1031,1032,1033,
1034,1035,1036,1037,1038,1039,1040,1041,1042,1043,1044,1045,1046,1047,1048,1049,
1050,1051,1052,1053,1054,1055,1056,1057,1058,1059,1060,1061,1062,1063,1064,1065,
1066,1067,1068,1069,1070,1071,1072,1073,1074,1075,1076,1077,1078,1079,1080,1081,
1082,1083,1084,1085,1086,1087,1088,1089,1090,1091,1092,1093,1094,1095,1096,1097,
1098,1099,1100,1101,1102,1103,1104,1105,1106,1107,1108,1109,1110,1111,1112,1113,
1114,1115,1116,1117,1118,1119,1120,1121,1122,1123,1124,1125,1126,1127,1128,1129,
1130,1131,1132,1133,1134,1135,1136,1137,1138,1139,1140,1141,1142,1143,1144,1145,
1146,1147,1148,1149,1150,1151,1152,1153,1154,1155,1156,1157,1158,1159,1160,1161,
1162,1163,1164,1165,1166,1167,1168,1169,1170,1171,1172,1173,1174,1175,1176,1177,
1178,1179,1180,1181,1182,1183,1184,1185,1186,1187,1188,1189,1190,1191,1192,1193,
1194,1195,1196,1197,1198,1199,1200,1201,1202,1203,1204,1205,1206,1207,1208,1209,
1210,1211,1212,1213,1214,1215,1216,1217,1218,1219,1220,1221,1222,1223,1224,1225,
1226,1227,1228,1229,1230,1231,1232,1233,1234,1235,1236,1237,1238,1239,1240,1241,
1242,1243,1244,1245,1246,1247,1248,1249,1250,1251,1252,1253,1254,1255,1256,1257,
1258,1259,1260,1261,1262,1263,1264,1265,1266,1267,1268,1269,1270,1271,1272,1273,
1274,1275,1276,1277,1278,1279,1280,1281,1282,1283,1284,1285,1286,1287,1288,1289,
1290,1291,1292,1293,1294,1295,1296,1297,1298,1299,1300,1301,1302,1303,1304,1305,
1306,1307,1308,1309,1310,1311,1312,1313,1314,1315,1316,1317,1318,1319,1320,1321,
1322,1323,1324,1325,1326,1327,1328,1329,1330,1331,1332,1333,1334,1335,1336,1337,
1338,1339,1340,1341,1342,1343,1344,1345,1346,1347,1348,1349,1350,1351,1352,1353,
1354,1355,1356,1357,1358,1359,1360,1361,1362,1363,1364,1365,1366,1367,1368,1369,
1370,1371,1372,1373,1374,1375,1376,1377,1378,1379,1380,1381,1382,1383,1384,1385,
1386,1387,1388,1389,1390,1391,1392,1393,1394,1395,1396,1397,1398,1399,1400,1401,
1402,1403,1404,1405,1406,1407,1408,1409,1410,1411,1412,1413,1414,1415,1416,1417,
1418,1419,1420,1421,1422,1423,1424,1425,1426,1427,1428,1429,1430,1431,1432,1433,
1434,1435,1436,1437,1438,1439,1440,1441,1442,1443,1444,1445,1446,1447,1448,1449,
1450,1451,1452,1453,1454,1455,1456,1457,1458,1459,1460,1461,1462,1463,1464,1465,
1466,1467,1468,1469,1470,1471,1472,1473,1474,1475,1476,1477,1478,1479,1480,1481,
1482,1483,1484,1485,1486,1487,1488,1489,1490,1491,1492,1493,1494,1495,1496,1497,
1498,1499,1500,1501,1502,1503,1504,1505,1506,1507,1508,1509,1510,1511,1512,1513,
1514,1515,1516,1517,1518,1519,1520,1521,1522,1523,1524,1525,1526,1527,1528,1529,
1530,1531,1532,1533,1534,1535,1536,1537,1538,1539,1540,1541,1542,1543,1544,1545,
1546,1547,1548,1549,1550,1551,1552,1553,1554,1555,1556,1557,1558,1559,1560,1561,
1562,1563,1564,1565,1566,1567,1568,1569,1570,1571,1572,1573,1574,1575,1576,1577,
1578,1579,1580,1581,1582,1583,1584,1585,1586,1587,1588,1589,1590,1591,1592,1593,
1594,1595,1596,1597,1598,1599,1600,1601,1602,1603,1604,1605,1606,1607,1608,1609,
1610,1611,1612,1613,1614,1615,1616,1617,1618,1619,1620,1621,1622,1623,1624,1625,
1626,1627,1628,1629,1630,1631,1632,1633,1634,1635,1636,1637,1638,1639,1640,1641,
1642,1643,1644,1645,1646,1647,1648,1649,1650,1651,1652,1653,1654,1655,1656,1657,
1658,1659,1660,1661,1662,1663,1664,1665,1666,1667,1668,1669,1670,1671,1672,1673,
1674,1675,1676,1677,1678,1679,1680,1681,1682,1683,1684,1685,1686,1687,1688,1689,
1690,1691,1692,1693,1694,1695,1696,1697,1698,1699,1700,1701,1702,1703,1704,1705,
1706,1707,1708,1709,1710,1711,1712,1713,1714,1715,1716,1717,1718,1719,1720,1721,
1722,1723,1724,1725,1726,1727,1728,1729,1730,1731,1732,1733,1734,1735,1736,1737,
1738,1739,1740,1741,1742,1743,1744,1745,1746,1747,1748,1749,1750,1751,1752,1753,
1754,1755,1756,1757,1758,1759,1760,1761,1762,1763,1764,1765,1766,1767,1768,1769,
1770,1771,1772,1773,1774,1775,1776,1777,1778,1779,1780,1781,1782,1783,1784,1785,
1786,1787,1788,1789,1790,1791,1792,1793,1794,1795,1796,1797,1798,1799,1800,1801,
1802,1803,1804,1805,1806,1807,1808,1809,1810,1811,1812,1813,1814,1815,1816,1817,
1818,1819,1820,1821,1822,1823,1824,1825,1826,1827,1828,1829,1830,1831,1832,1833,
1834,1835,1836,1837,1838,1839,1840,1841,1842,1843,1844,1845,1846,1847,1848,1849,
1850,1851,1852,1853,1854,1855,1856,1857,1858,1859,1860,1861,1862,1863,1864,1865,
1866,1867,1868,1869,1870,1871,1872,1873,1874,1875,1876,1877,1878,1879,1880,1881,
1882,1883,1884,1885,1886,1887,1888,1889,1890,1891,1892,1893,1894,1895,1896,1897,
1898,1899,1900,1901,1902,1903,1904,1905,1906,1907,1908,1909,1910,1911,1912,1913,
1914,1915,1916,1917,1918,1919,1920,1921,1922,1923,1924,1925,1926,1927,1928,1929,
1930,1931,1932,1933,1934,1935,1936,1937,1938,1939,1940,1941,1942,1943,1944,1945,
1946,1947,1948,1949,1950,1951,1952,1953,1954,1955,1956,1957,1958,1959,1960,1961,
1962,1963,1964,1965,1966,1967,1968,1969,1970,1971,1972,1973,1974,1975,1976,1977,
1978,1979,1980,1981,1982,1983,1984,1985,1986,1987,1988,1989,1990,1991,1992,1993,
1994,1995,1996,1997,1998,1999,2000) as t;
+---+
| t |
+---+
| 1 |
+---+
1 row in set (0.00 sec)mysql>
'截至2010-10-22 17:22:59 用户结帖率0.00%
当您的问题得到解答后请及时结贴.
http://topic.csdn.net/u/20090501/15/7548d251-aec2-4975-a9bf-ca09a5551ba5.html
http://topic.csdn.net/u/20100428/09/BC9E0908-F250-42A6-8765-B50A82FE186A.html
http://topic.csdn.net/u/20100626/09/f35a4763-4b59-49c3-8061-d48fdbc29561.html8、如何给分和结贴？
http://community.csdn.net/Help/HelpCenter.htm#结帖