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/* |
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** Copyright (c) 2007 D. Richard Hipp |
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** |
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** This program is free software; you can redistribute it and/or |
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** modify it under the terms of the Simplified BSD License (also |
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** known as the "2-Clause License" or "FreeBSD License".) |
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** This program is distributed in the hope that it will be useful, |
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** but without any warranty; without even the implied warranty of |
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** merchantability or fitness for a particular purpose. |
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** |
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** Author contact information: |
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** [email protected] |
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** http://www.hwaci.com/drh/ |
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** |
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******************************************************************************* |
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** |
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** This file contains code used to find the most recent common |
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** ancestor of time versions of the same file. We call this |
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** common ancestor the "pivot" in a 3-way merge. |
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*/ |
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#include "config.h" |
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#include "pivot.h" |
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#include <assert.h> |
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/* |
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** Set the primary file. The primary version is one of the two |
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** files that have a common ancestor. The other file is the secondary. |
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** There can be multiple secondaries but only a single primary. |
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** The primary must be set first. |
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** |
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** In the merge algorithm, the file being merged in is the primary. |
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** The current check-out or other files that have been merged into |
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** the current check-out are the secondaries. |
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** |
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** The act of setting the primary resets the pivot-finding algorithm. |
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*/ |
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void pivot_set_primary(int rid){ |
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/* Set up table used to do the search */ |
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db_multi_exec( |
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"CREATE TEMP TABLE IF NOT EXISTS aqueue(" |
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" rid INTEGER," /* The record id for this version */ |
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" mtime REAL," /* Time when this version was created */ |
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" pending BOOLEAN," /* True if we have not check this one yet */ |
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" src BOOLEAN," /* 1 for primary. 0 for others */ |
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" PRIMARY KEY(rid,src)" |
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") WITHOUT ROWID;" |
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"DELETE FROM aqueue;" |
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"CREATE INDEX IF NOT EXISTS aqueue_idx1 ON aqueue(pending, mtime);" |
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); |
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/* Insert the primary record */ |
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db_multi_exec( |
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"INSERT INTO aqueue(rid, mtime, pending, src)" |
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" SELECT %d, mtime, 1, 1 FROM event WHERE objid=%d AND type='ci' LIMIT 1", |
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rid, rid |
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); |
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} |
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/* |
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** Set a secondary file. The primary file must be set first. There |
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** must be at least one secondary but there can be more than one if |
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** desired. |
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*/ |
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void pivot_set_secondary(int rid){ |
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/* Insert the secondary record */ |
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db_multi_exec( |
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"INSERT OR IGNORE INTO aqueue(rid, mtime, pending, src)" |
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" SELECT %d, mtime, 1, 0 FROM event WHERE objid=%d AND type='ci'", |
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rid, rid |
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); |
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} |
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/* |
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** Find the most recent common ancestor of the primary and one of |
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** the secondaries. Return its rid. Return 0 if no common ancestor |
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** can be found. |
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** |
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** If ignoreMerges is true, follow only "primary" parent links. |
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*/ |
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int pivot_find(int ignoreMerges){ |
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Stmt q1, q2, u1, i1; |
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int rid = 0; |
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/* aqueue must contain at least one primary and one other. Otherwise |
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** we abort early |
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*/ |
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if( db_int(0, "SELECT count(distinct src) FROM aqueue")<2 ){ |
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fossil_fatal("lack both primary and secondary files"); |
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} |
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/* Prepare queries we will be needing |
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** |
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** The first query finds the oldest pending version on the aqueue. This |
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** will be next one searched. |
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*/ |
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db_prepare(&q1, "SELECT rid FROM aqueue WHERE pending" |
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" ORDER BY pending DESC, mtime DESC"); |
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/* Check to see if the record :rid is a common ancestor. The result |
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** set contains one or more rows if it is and is the empty set if it |
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** is not. |
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*/ |
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db_prepare(&q2, |
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"SELECT 1 FROM aqueue A, plink, aqueue B" |
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" WHERE plink.pid=:rid" |
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" AND plink.cid=B.rid" |
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" AND A.rid=:rid" |
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" AND A.src!=B.src %s", |
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ignoreMerges ? "AND plink.isprim" : "" |
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); |
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/* Mark the :rid record has having been checked. It is not the |
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** common ancestor. |
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*/ |
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db_prepare(&u1, |
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"UPDATE aqueue SET pending=0 WHERE rid=:rid" |
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); |
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/* Add to the queue all ancestors of :rid. |
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*/ |
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db_prepare(&i1, |
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"REPLACE INTO aqueue " |
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"SELECT plink.pid," |
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" coalesce((SELECT mtime FROM event X WHERE X.objid=plink.pid), 0.0)," |
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" 1," |
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" aqueue.src " |
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" FROM plink, aqueue" |
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" WHERE plink.cid=:rid" |
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" AND aqueue.rid=:rid %s", |
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ignoreMerges ? "AND plink.isprim" : "" |
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); |
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while( db_step(&q1)==SQLITE_ROW ){ |
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rid = db_column_int(&q1, 0); |
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db_reset(&q1); |
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db_bind_int(&q2, ":rid", rid); |
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if( db_step(&q2)==SQLITE_ROW ){ |
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break; |
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} |
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db_reset(&q2); |
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db_bind_int(&i1, ":rid", rid); |
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db_exec(&i1); |
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db_bind_int(&u1, ":rid", rid); |
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db_exec(&u1); |
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rid = 0; |
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} |
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db_finalize(&q1); |
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db_finalize(&q2); |
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db_finalize(&i1); |
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db_finalize(&u1); |
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return rid; |
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} |
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/* |
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** COMMAND: merge-base |
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** |
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** Usage: %fossil merge-base ?options? PRIMARY SECONDARY ... |
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** |
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** Find a common ancestor given two or more check-in versions to |
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** hypothetically merge. |
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** |
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** Options: |
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** --ignore-merges Ignore merges for discovering name pivots |
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*/ |
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void merge_base_cmd(void){ |
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int i, rid; |
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int ignoreMerges = find_option("ignore-merges",0,0)!=0; |
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int showDetails = find_option("details",0,0)!=0 |
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/* intentionally undocumented */; |
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if( g.argc<4 ){ |
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usage("?options? PRIMARY SECONDARY ..."); |
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} |
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db_must_be_within_tree(); |
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pivot_set_primary(name_to_rid(g.argv[2])); |
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for(i=3; i<g.argc; i++){ |
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pivot_set_secondary(name_to_rid(g.argv[i])); |
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} |
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rid = pivot_find(ignoreMerges); |
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if( rid==0 ){ |
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puts("No common ancestor found."); |
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}else{ |
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printf("pivot=%s\n", |
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db_text("?","SELECT uuid FROM blob WHERE rid=%d",rid)); |
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} |
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if( showDetails ){ |
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Stmt q; |
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db_prepare(&q, |
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"SELECT substr(uuid,1,12), aqueue.rid, datetime(aqueue.mtime)," |
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" aqueue.pending, aqueue.src\n" |
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" FROM aqueue JOIN blob ON aqueue.rid=blob.rid\n" |
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" ORDER BY aqueue.mtime DESC" |
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); |
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while( db_step(&q)==SQLITE_ROW ){ |
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printf("\"%s\",%d,\"%s\",%d,%d\n", |
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db_column_text(&q, 0), |
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db_column_int(&q, 1), |
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db_column_text(&q, 2), |
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db_column_int(&q, 3), |
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db_column_int(&q, 4)); |
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} |
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db_finalize(&q); |
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} |
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} |
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