Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -2157,12 +2157,16 @@
 ** is harmless.  A false positive, however, can result in the wrong
 ** answer.
 */
 int sqlite3ExprNeedsNoAffinityChange(const Expr *p, char aff){
   u8 op;
+  int unaryMinus = 0;
   if( aff==SQLITE_AFF_BLOB ) return 1;
-  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){ p = p->pLeft; }
+  while( p->op==TK_UPLUS || p->op==TK_UMINUS ){
+    if( p->op==TK_UMINUS ) unaryMinus = 1;
+    p = p->pLeft;
+  }
   op = p->op;
   if( op==TK_REGISTER ) op = p->op2;
   switch( op ){
     case TK_INTEGER: {
       return aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC;
@@ -2169,14 +2173,14 @@
     }
     case TK_FLOAT: {
       return aff==SQLITE_AFF_REAL || aff==SQLITE_AFF_NUMERIC;
     }
     case TK_STRING: {
-      return aff==SQLITE_AFF_TEXT;
+      return !unaryMinus && aff==SQLITE_AFF_TEXT;
     }
     case TK_BLOB: {
-      return 1;
+      return !unaryMinus;
     }
     case TK_COLUMN: {
       assert( p->iTable>=0 );  /* p cannot be part of a CHECK constraint */
       return p->iColumn<0
           && (aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC);

Index: test/affinity2.test
==================================================================
--- test/affinity2.test
+++ test/affinity2.test
@@ -82,7 +82,39 @@
   INSERT INTO t3 VALUES(5, 1, 1);
 }
 do_execsql_test 440 {
   SELECT * FROM t3 WHERE c='0' ORDER BY a;
 } {2 1 0 4 1 0}
+
+# 2019-08-22 ticket https://sqlite.org/src/info/d99f1ffe836c591ac57f
+# False positive in sqlite3ExprNeedsNoAffinityChange()
+#
+do_execsql_test 500 {
+  DROP TABLE IF EXISTS t0;
+  CREATE TABLE t0(c0 TEXT UNIQUE, c1);
+  INSERT INTO t0(c0) VALUES (-1);
+  SELECT quote(- x'ce'), quote(t0.c0), quote(- x'ce' >= t0.c0) FROM t0;
+} {0 '-1' 1}
+do_execsql_test 501 {
+  SELECT * FROM t0 WHERE - x'ce' >= t0.c0;
+} {-1 {}}
+do_execsql_test 502 {
+  SELECT quote(+-+x'ce'), quote(t0.c0), quote(+-+x'ce' >= t0.c0) FROM t0;
+} {0 '-1' 1}
+do_execsql_test 503 {
+  SELECT * FROM t0 WHERE +-+x'ce' >= t0.c0;
+} {-1 {}}
+do_execsql_test 504 {
+  SELECT quote(- 'ce'), quote(t0.c0), quote(- 'ce' >= t0.c0) FROM t0;
+} {0 '-1' 1}
+do_execsql_test 505 {
+  SELECT * FROM t0 WHERE - 'ce' >= t0.c0;
+} {-1 {}}
+do_execsql_test 506 {
+  SELECT quote(+-+'ce'), quote(t0.c0), quote(+-+'ce' >= t0.c0) FROM t0;
+} {0 '-1' 1}
+do_execsql_test 507 {
+  SELECT * FROM t0 WHERE +-+'ce' >= t0.c0;
+} {-1 {}}
+ 
 
 finish_test