SELECT count(distinct c) as nb FROM t_asv where b = 21 group by b
1 The words of the Preacher, the son of David, king in Jerusalem. 2 Vanity of vanities, saith the Preacher; vanity of vanities, all is vanity. 3 What profit hath man of all his labor wherein he laboreth under the sun? 4 One generation goeth, and another generation cometh; but the earth abideth for ever. 5 The sun also ariseth, and the sun goeth down, and hasteth to its place where it ariseth. 6 The wind goeth toward the south, and turneth about unto the north; it turneth about continually in its course, and the wind returneth again to its circuits. 7 All the rivers run into the sea, yet the sea is not full; unto the place whither the rivers go, thither they go again. 8 All things are full of weariness; man cannot utter `it': the eye is not satisfied with seeing, nor the ear filled with hearing. 9 That which hath been is that which shall be; and that which hath been done is that which shall be done: and there is no new thing under the sun. 10 Is there a thing whereof it may be said, See, this is new? it hath been long ago, in the ages which were before us. 11 There is no remembrance of the former `generations'; neither shall there be any remembrance of the latter `generations' that are to come, among those that shall come after. 12 I the Preacher was king over Israel in Jerusalem. 13 And I applied my heart to seek and to search out by wisdom concerning all that is done under heaven: it is a sore travail that God hath given to the sons of men to be exercised therewith. 14 I have seen all the works that are done under the sun; and, behold, all is vanity and a striving after wind. 15 That which is crooked cannot be made straight; and that which is wanting cannot be numbered. 16 I communed with mine own hear, saying, Lo, I have gotten me great wisdom above all that were before me in Jerusalem; yea, my heart hath had great experience of wisdom and knowledge. 17 And I applied my heart to know wisdom, and to know madness and folly: I perceived that this also was a striving after wind. 18 For in much wisdom is much grief; and he that increaseth knowledge increaseth sorrow.